In April 2021 West Coast Placer was hired to assist in exploration for a large-scale alluvial gold project in Sierra Leone, West Africa. This program took place in the Kono region of Sierra Leone which hosts diamonds as well as gold in their placer deposits. It was a great experience and it was really cool to see how they do things in West Africa compared to the West Coast of North America.
Sierra Leone is famous for its alluvial diamonds. We were working in the Kono district which is where the plot of the movie Blood Diamond took place. The region where Leonardo DiCaprio’s character died at the end (spoiler alert) is not far from the survey area that we were exploring.
Despite extensive diamond mining taking place in the region since the 1930s very little attention had been paid to the alluvial gold deposits. There are a lot of artisanal miners active in the area but their sole focus is diamonds and they often discard the gold that they dig up. That fact surprised me because even in Canada where the average income and standard of living is much, much higher nobody would ever throw gold back into a river. That’s one of many things that’s different in Africa.
The placer deposits in the Kono region are much older than anything in BC or the Yukon. Much of the bedrock is Precambrian (500 million to 4 billion years old) and hasn’t ever been glaciated. By contrast, the rock in BC is less than 200 million years old and has been bulldozed by large glaciers on at least 4 occasions. Despite the differences, some things are the same in pretty much every placer environment. Over time rivers and streams move and leave their gold deposits behind in ancient paleochannels. That’s what we were looking for. Our system is designed to map bedrock depth and show the location of paleochannels.
Travelling internationally during the covid-19 pandemic is quite an adventure. In April 2021 the vaccines weren’t available yet and travel restrictions were very tough. We had to do lots of covid tests at each leg of the journey and there were a few hiccups. One of our team members wasn’t allowed to board the flight to Belgium from Montreal because his test was taken too far in advance. He had to get another PCR test and catch a flight the next day. On the way back I almost had to stay in a covid hotel, fortunately, the Canadian government honored my essential service exemption.
It was interesting that Sierra Leone didn’t have a lot of covid restrictions. That’s because three years prior to the breakout of Covid -19 around the world West Africa was center stage to the worst ebola outbreak in history. When covid broke out in 2020 they knew what to do and locked the whole country down with no exceptions. By the time we arrived in 2021 the whole country had a total case count of 80 and zero deaths. With the intense screening protocols for international travellers they were able to keep infection rates to a minimum, something that wealthy western countries weren’t able to do, even with the advent of vaccines.
We spent a few nights in the capital city of Freetown and headed off to Koidu Town to begin our exploration. The bedrock mapping survey covered a large area that was chosen due to the prevalence of artisinal mining and topographic features that favoured the development of paleochannels. We had some knowledge of hard rock gold production in the area and anecdotal evidence from local artisanal placer miners.
We had a crew of local laborers which included the son of the Paramount Chief. That was important for public relations since we didn’t speak the local language and it was important to explain to the villagers what we were doing. Having the chief on our side let everyone know that we were working along with local government and not just rolling in to take all the resources for ourselves.
Sierra Leone is ruled by a combination of federal government and chiefdoms. The mining claims are managed by both levels of government in a complex way. Without the support of the chief it would be hard to get the necessary permitting and support of the local community. Luckily for us, the local chief is a miner himself and we got along really well.
The artisanal miners do a lot of the work by hand. They often use gas-powered water pumps similar to what small-scale miners use in Canada. Mostly for dewatering though, they don’t have highbankers like we do back home. In Africa people carry everything on their heads, even the water pumps.
Most of the washing is done by hand using gem screens or large gold pans. The larger operations use a rudimentary hydrostatic jig. There are very few operations using heavy equipment but manpower is readily available in this area.
The local miners have a method of digging shafts that works really well in the clay-rich gravels in that area. They dig a shaft about 1 meter wide and dig out foot holds on the way down. In this way they can reach bedrock in a day or two and get really good samples from the bedrock interface. The company that we were working with hired a large crew of local miners to dig shafts instead of using a drill. The samples were better and expert shaft diggers were more than willing to work for $10 US per day.
Getting supplies in a third world country can be an adventure in itself. We tried to bring everything that we needed with us but we counted on procuring some supplies locally. One thing that we need lots of was flagging tape. Since this is a mining area we thought it wouldn’t be too hard to find. It turns out that there is no flagging tape available for sale in the entire city of Koidu. Despite two full-scale kimberlite mines right next to the city. We had to buy fabric ribbon in bright colours and use scissors to cut it in order to mark our lines.
It turned out that the local kids like the fabric just as much as we did since they would come right behind us and pull all the ribbon off the lines as soon as we were done. Sometimes they wouldn’t even wait till we had completed the line which made a few sections really challenging.
Some of the more high tech mining devices in Africa are really cool. The company had some really efficient gold centrifuges for testing the gravels. They’re like a gravity concentrator that you see in North America but made to be economical and easy to deploy. One machine is called the Gold Kacha and works really well.
Centrifuges aren’t commonly used in placer mining in BC and the Yukon but that’s something that we should really consider. The gravity concentrators on the market are expensive in Canada but you can get a Gold Kacha out of South Africa for about the same price ad an average highbanker setup here in BC.
The local gold panning technique is quite different from what I’m used to. They use a large rounded bowl with handles on the sides. There are no riffles and the sides have a very gentle slope. My technique didn’t work to well with their pans. The local technique is to swirl the material in the pan while letting the lighter stuff wash over the sides. One of my crew members demonstrated the technique in the video below.
The bedrock mapping survey was a huge success. We identified a clear paleo-valley and an ancient river channel that spanned several kilometers. Much of the area that we identified with the seismic survey as an ancient channel had never been exploited by artisanal miners.
One great thing about working in Sierra Leone is you don’t need permits as you do in BC. We were able to start digging with an excavator right away. With a combination of bulk sampling with the excavator and teams of local shaft diggers sampling was completed in less than a month. The gold grades within the channel were excellent and alluvial diamonds were also present.
Exploring a new area is always a welcome experience. As explorers, we are constantly striving to search different areas and locate mineable gold deposits. This exploration program in West Africa did not disappoint. It was quite a contrast to use the latest technologies in an area where people are still living in mud huts and cooking with charcoal. Some of the ancient techniques used in Sierra Leone are very efficient, such as the shaft digging technique. If we could get hundreds of workers to dig shafts in Canada for $10 per day imagine the ground that could be explored.
We managed to locate a very rich placer deposit containing minable quantities of gold and alluvial diamonds. This project was developed with the support and mutual benefit of the local chiefdom and communities. It was a great experience to share knowledge of different mining and exploration techniques and learn a few new ones as well.
Finding an ancient river channel is the holy grail of placer gold exploration. If you’re in a gold-bearing area, old river channels can hold the kind of unlocked treasures that dreams are made of. Prior to the gold rushes of the mid-1800s, you could have walked up to a virgin stream with untouched gold nuggets sitting in the bottom. That is an extremely rare discovery today. Ancient river channels are hard to find but that’s why many channels are still undisturbed waiting for a smart prospector to discover them.
There are undiscovered paleochannels hidden to the naked eye all over the goldfields of North America, and other gold placer districts all over the globe. Advances in technology have aided in the discovery of these ancient channels, some of the tried and true methods still hold true today. How can you find something that you can’t see? This article will explain what paleochannels are and how we find them.
Paleochannels have many names. Such as:
Ancient Rivers of Gold
Some of those terms refer to specific ages or other characteristics of the channels but they all basically refer to the same thing, river beds that have run dry and have been buried by sediment. There are lots of reasons why a river might change its course but the end result is more or less the same.
The definition of a paleochannel is:
a remnant of an inactive river or stream channel that has been filled or buried by younger sediment
Paleochannels can form in many ways. Either slowly over time or abruptly from things like tectonic activity, glacial dams, mudslides, volcanic eruptions, or by human intervention.
When reading about ancient channels there are terms that often come up such as preglacial, periglacial, tertiary, quaternary, and many others. Those are just adding a time period to the formation of these channels, they’re really all the same thing. “Tertiary channels” are often written about in western North America, but that just means they are ancient channels that were formed during the tertiary period. The tertiary period ranged from the time of the extinction of the dinosaurs (the K-T extinction) about 66 million years ago to the beginning of the ice age period about 2.6 million years ago.
The quaternary period is more recent ranging from 2.6 million years ago to today and has experienced several periods of glaciation. The Pleistocene and Holocene are also part of the Quaternary Period.
Preglacial and Periglacial refer to the timing of a channel in relation to a glacial period. Approximately a dozen major glaciations have occurred over the past 1 million years, the largest of which peaked 650,000 years ago and lasted for 50,000 years. The most recent glaciation period, often known simply as the “Ice Age,” reached peak conditions some 18,000 years ago before giving way to the interglacial Holocene epoch 11,700 years ago.
People sometimes get hung up on some of the terminology but whether a channel formed in a specific time period doesn’t make a huge difference to a placer miner. To be honest, when it comes to placer exploration, every ancient channel in a gold-bearing area is worth exploring, regardless of the age. A channel that only formed 100 years ago has the same likelihood of containing placer gold as one that formed 3 million years ago during the tertiary period. What really matters is whether the creek that formed the channel carried gold or not.
A familiar feature that resembles a paleochannel is an oxbow lake. These formations occur when a meander in a river gets cut off. You can observe oxbow lakes in many places, eventually, the lake will run dry and you’ll end up with a buried paleochannel. Oxbows can be gold-bearing even though they are not considered a “paleochannel”. Streams meander and change course frequently, in some places you can watch oxbows forming in near real-time.
Rivers and streams form all kinds of channels, for different reasons but they all have some things in common. A paleochannel is really the same thing as the rivers and streams that you see today, it was just rerouted and buried by sediment. When prospecting a paleochannel the same rules apply, the old river had inside bends, exposed bedrock, boulders, etc.
The character of a Paleochannel
There are several characteristics that make up a paleochannel. They can tell you a lot about its setting and the depositional environment, which in turn can give you a good idea if placer gold will be present or not.
Those characteristics are width, sinuosity, thalweg, slope, and age.
Channel width is an important metric for characterizing streamflow and depositional environment. The width is measured perpendicular to the centerline from bank to bank. The width can tell you a lot about a channel, especially when combined with other factors.
Sinuosity is the measure of how much a channel meanders. The sinuosity is measured by dividing the channel length by the straight line distance down the valley axis. You can infer the slope, transport capacity, and other factors from the sinuosity alone. More sinuous channels, those that meander a lot, occur on gentle slopes, the straighter the channel, the steeper the slope.
Thalweg is a funny word that comes from German meaning “valley way”. Don’t ask me why we use a German word but we do. The thalweg is simply the deepest part of the channel which is colloquially referred to as the “gutter”.
The slope, along with the width and sinuosity is used to calculate the ability of a channel to transport sediment. The slope is the average angle of the valley in which a stream lies. From a placer standpoint, we know that if our sluice box is too steep the gold won’t catch in the matting, if it’s too shallow the sediment won’t clear. A creek is no different.
The famous California goldfield geologist, Waldemar Lindgren studied channel slopes in relation to placer deposits in BC, California, and the Yukon in 1933. Lindgren determined that the optimal slope for placer formation is a 30-foot drop to the mile or 6 meters per kilometer which calculates out to a ratio of 0.06 or 0.34°. The Klondike’s Bonanza Creek averages 50 feet to the mile (0.01). Dominion Creek, in the Klondike, averages .02; there are slope breaks to 0.01 and that is where most of the gold was trapped. Almost all placer-bearing channels in BC range from a slope of 0.02 to 0.10.
Types of Paleochannels
Bench Channels occur on high benches or terraces above a current river. The flat benches represent the ancient valley floor. As river valley systems evolve the river cuts deeper and deeper into the bedrock leaving old channels high and dry. If you retrace the history the old river would have sat at a higher elevation than it does today.
Bench channels typically have a single channel and aren’t braided. The slope, sinuosity, and width tend to be similar to the current stream. These paleochannels typically run parallel to the existing steam but not always.
High benches can be observed in many river systems in western North America and many rich paleochannels have been discovered and mined within them.
Buried Paleochannels within modern valleys can be adjacent to or underneath an existing alluvial stream within the same valley. The extent of these channels is difficult to determine due to the complexity of their setting. These channels can be very deep and sometimes buried under several different glacial or fluvial events. The sinuosity, width, slope and direction often mirrors that of the existing stream but not always.
These channels are difficult to mine due to the continual flow of water from the existing stream. A bedrock drain or lots of pumping is often required.
A great example of this type of paleochannel is the Wingdam Mine on Lightning Creek in the Cariboo. Omineca Mining and Metals has found a unique solution to mining their deposit, check out the video below.
Paleogulches are another type of ancient channel. They are gulches that dried up and were buried by sediment. Paleogulches have steep sides and a relatively steep gradient. They have low sinuosity and a relatively straight path. The channel often runs on or near bedrock due to the steep slope of the thalweg and high flow rate.
Gold in these deposits is usually coarse and hasn’t traveled far from the source. Paleogulch placers, like other buried-channel deposits, are typically covered by thick deposits of till, glaciofluvial deposits, and glaciolacustrine sediments.
Paleotrunk-valleys are similar to the paleogulches above. They are trunk valleys that were abandoned and filled with sediment. These deposits are often hundreds of meters wide and quite deep. Paleotrunk-valleys typically no longer have a stream running in them and tend to be totally filled with sediment leaving little to no surface expression.
The Bullion hydraulic mine near Likely, BC is an example of this type of paleochannel. The Bullion Pit produced over 120,000 ounces of gold over the lifespan of the mine. The famous Mary Creek deposit is another example of this type.
Inverted Paleochannels form in a totally different way. They sit high above the surroundings but not on a bench, and not in an existing valley, at least not usually. This type of paleochannel forms when a river valley is filled with lava from a volcanic eruption. The resulting lava cools into basalt and forms a protective cap that is much stronger than the surrounding rock. The result is that over time the surrounding rock is eroded but the basalt is much more resistant and protects the sedimentary rock below it, leaving a high ridge where the river used to be.
Inverted channels are more common in the southwestern United States in places like Utah, Idaho, and eastern Washington. I’m not aware of any gold deposits from inverted channels but it is possible.
An important note about paleochannels: not every channel contains gold. There are paleochannels all over the earth, only ones in gold-bearing areas are significant for gold prospecting. After all, the ancient channel won’t contain gold unless the creek that created it carried gold in its sediment load.
Most parts of North America have been exposed to glaciation at some time or another. The more northern parts have seen extreme transformations of the landscape due to glaciers scouring the surface of the earth. This makes finding ancient channels a lot harder.
It’s rare to find an entire river system entombed in sediment in BC, for example. What you usually find are fragments of ancient rivers. Some can be only a few hundred meters long while others can stretch for 10s of kilometers. There are often pieces missing due to glacial or other types of erosion.
The job of the prospector when exploring an ancient channel isn’t too different from a crime scene investigator on CSI. You’re dealing with fragments of channels and what you want to do is add up the clues to reconstruct the crime scene. Modern prospectors use a variety of tools to put those clues together.
How to find a paleochannel
Now we know the types of channels and a little bit about them. How do we find a paleochannel that we can mine?
One of the tell-tale signs of a paleochannel is finding compacted river gravels in an exposed bank. If you’re in the right place and you’re lucky enough to come across river gravels in an exposed bank you could have discovered an ancient channel. Old river beds have certain characteristics that differ from other materials that you’d often see in an exposed bank.
An old river bed will have the following features:
Rounded river rocks
Sorted by size
River beds look different than glacial till, for example. Till will generally have different sized rocks randomly jumbled together, not sorted. Till can have rounded rocks but they are usually accompanied by angular rock of different sizes. A river bed should have bigger rocks at the bottom and finer, rounded gravels on top. River beds are packed together similar to the way that a brick wall is put together, everything fits together tightly with sand and gravel filling in the gaps. It’s not always totally obvious but if you see these signs it’s worth exploring further.
Spotty pay is another potential sign of a paleochannel. If there are sections of a creek that pay well and contain really good gold while other sections are barren that can be due to a rich paleochannel. Sometimes rivers don’t carry any gold of their own but redeposit gold from an ancient channel. It’s also possible that gold is washing down from a hardrock deposit, either way it can pay off big time to investigate spotty pay areas. The same is true when there are several creeks close together and they only have placer gold in a certain region on each creek. If the hot spots on several creeks line up there is probably a reason and it could be that the creeks all cut through a hidden paleochannel.
The old-time miners often discovered ancient channels by digging shafts by hand. Many channels have been discovered in this way. It’s not very effective by today’s standards but some people still use this technique. The presence of compacted river gravels underneath layers of sediment are a good sign that a paleochannel is present.
The old-timers would often dig numerous shafts looking for a channel and would dig a horizontal shaft known as a drift once a channel is located. That involves a lot of backbreaking physical work with a low chance of success but during the 1800s and early 1900s, there weren’t as many options available as there are today.
Here’s a great 5-minute YouTube video that describes what compacted river gravels look like, as well as some of the geology at play:
The modern prospector can benefit from advances in technology, especially computer mapping and GIS. Modern mapping tools such as Google Terrain maps can help to find the habitat where paleochannels are likely to be present. LiDAR and drone-based high-resolution terrain mapping can give highly detailed terrain maps which aid in locating favorable conditions for paleochannel exploration.
For example, river benches as described above can often be seen on topo maps. It’s unlikely to see a channel outright since they rarely have a clear surface expression, if at all, but you can narrow down the search area by looking at terrain that is favorable for channels to occur.
Once the search area has been narrowed down to a specific area more advanced techniques can be used to map the exact location and depth of a paleochannel.
There are several geophysical techniques that can map underground structures without having to excavate down to the channel level. Geophysics uses a variety of techniques to map the subsurface of the earth. Some work better than others for mapping paleochannels.
Magnetometer surveys have been used on many occasions to attempt to map ancient channels. A magnetometer is an instrument that measures changes in earth’s magnetic field. They are commonly used in hard rock exploration due to their rapid speed and relatively low cost. Magnetic survey results are usually presented in a map that looks like a thermal image except that instead of temperature you’re looking at variation in the magnetic field, measured in nano-tesla (nT). When exploring for a paleochannel the concept relies on trying to pick up the magnetic signature of concentrations of black sand. The survey usually involves recording measurements along lines perpendicular to the channel and looking in the processed data for anomalous magnetic highs where black sand concentrations are present.
Magnetic surveys have been used a lot in the past but have a very low success rate for mapping paleochannels. This is largely due to false positives from surrounding rock and weak concentrations of mineral sands. I haven’t seen any of these surveys that have actually been successful in locating a paleochannel on their own.
Ground penetrating radar (GPR) is another popular technique. GPR uses a system with two components, a radar source and a receiver. The GPR source emits radio energy of a specific frequency and the receiver records reflections of subsurface rock and soil layers. The survey is laid out in a similar way, with lines perpendicular to the channel.
GPR has also been used in many exploration programs with limited success. Some channels have been discovered in this way but GPR has a few drawbacks. The signal is attenuated by groundwater, clay layers, and permafrost. Under perfect conditions, GPR can map a channel but the data is often ambiguous and of poor quality.
Electromagnetic techniques such as resistivity have a much higher success rate but they have similar issues to GPR when it comes to groundwater. Geoelectrical resistivity tomography (GRT) surveys have a much higher success rate than GPR or magnetometer surveys. The way they image the channels is a bit vague but many channels have been found with this technique. GRT has a few drawbacks as well, conductive bedrock, groundwater, and other factors can lead to unpredictable results.
Seismic surveys have the highest success rate for mapping paleochannels. Seismic works in a similar way to GPR but instead of radio waves it uses vibrational energy. There are two types of seismic used today. Refraction and passive seismic. Refraction surveys have been around for a long time and have been used to find many paleochannels with a very high rate of success. A refraction survey uses an energy source such as dynamite or a specialized shotgun to introduce energy into the ground. An array of sensors called geophones are laid out in a survey line to record the reflected waves that bounce back off the subsurface layers. The timing and velocity of seismic returns give information about the density of layers and their depth from the surface.
Seismic energy passes through groundwater, clay, permafrost with ease and if done correctly will accurately map the subsurface layers. The drawback to refraction seismic is the cost. It takes an experienced crew and expensive equipment to perform this survey correctly.
Passive seismic surveys are a new technique that has only started to be used in the last decade. The passive technique does not require an energy source and can be done with a much smaller crew at a fraction of the cost. Passive seismic is the new kid on the block but it has proven to be very effective at mapping hidden paleochannels. Passive surveys also remove the need to cut lines which lowers costs even more. More info on this technique here, bedrock mapping.
Once a channel is identified and the location is known, further testing is required. The above techniques are able to show the location, shape and character of a paleochannel but won’t give you any information about the gold content. For that you need to take actual samples.
Depending on the depth of the channel there are several options. If it’s shallow enough you can test with an excavator but that is rarely the most economical option. In most cases you need to drill.
There are several drilling techniques used in placer exploration and there are pros and cons to each.
Auger drills are popular among placer miners due to the relatively low cost and perceived sample size but they have serious drawbacks. Augers struggle with large rocks and boulders, and can’t usually penetrate bedrock. They also tend to ovalize the hole leading to sample contamination and material loss down the hole.
Sonic drills are the most effective option. A sonic drill uses a high frequency vibration to bore through soil and rock. These drills take undisturbed samples and can drill through gravel, boulders, and bedrock. You can’t beat the sample quality and efficiency of a sonic drill but the costs of this type of drilling can be quite high.
Reverse circulation (RC) drills also work really well. These drills use a downhole hammer that pulverizes the rock and gravel into chips which are pushed to a collection cyclone at the surface using pressurized air. RC drills also work really well for placer exploration. RC drilling has been used to successfully map many hidden paleochannels in BC and the Yukon.
Rotary diamond drills can also be used with specialized drill mud. These are less common than RC or sonic but have been successful in some situations.
Once you have identified the places where paleochannels are likely to occur from topographic maps, conducted geophysical surveys to map the channel and taken drill samples to confirm the channel depth and gold grades you’ll have the information necessary to develop a mining plan. If the gold grades are high enough to profitably mine then you’re ready to start production.
Many of the richest placer mines in the world exist on paleochannel deposits. They are notoriously difficult to locate and prospect but the results can be extraordinary. Advances in modern technology give today’s prospector an advantage that wasn’t available to miners in the past. There are hidden paleochannels in every mining district and even in places that have been mined for over a century. Discoveries are being made in places that nobody thought to look at in years past. Keep your eyes open for indications of an ancient river channel, there just might be a bonanza sitting right under your feet.
As prospectors, we have a deep connection to the past. We live in a world where technology has advanced to an amazing level. High tech devices that could only be imagined by science fiction authors a few decades ago are part of our everyday lives. Despite the current state of technological advancement, there is still no surefire way to detect unexplored gold deposits. Our pursuit of the yellow metal leaves no stone unturned. A good prospector will employ every tool at their disposal to get even the slightest edge in locating a gold deposit.
We look to the prospectors of the past and admire their ability to locate gold deposits with nothing more than their own ingenuity and a sense of adventure. Some techniques are no longer used and some haven’t changed for centuries. Dowsing fits somewhere in between. It’s always been a mystery. Nobody can explain how it works but many swear on their mother’s grave that it does.
Dowsing refers to the practice of using a forked stick, metal rod, pendulum, or similar device to locate underground water, minerals, or other hidden or lost substances, and has been a subject of discussion and controversy for
hundreds, if not thousands, of years. The practice is also called divining or witching. There is a history of mysticism, magic, and supernatural beliefs associated with the divining rod that dates back over 8,000 years.
In the Tassili Caves of northern Africa, an 8,000-year-old cave painting depicts a man holding a forked stick, apparently using it to search for water.
Divining rods were used by the Scythians, Persians, and Medes. The practice was used by Bavarian miners in the early 1500s and spread throughout Europe as their deep mining skills were highly sought after. Check out our article on Free Miners for a bit more info on that.
Controversy on the subject goes back to before medieval times. In 1518 Martin Luther listed the use of the divining rod as an act that broke the first commandment under the assumption that dowsing is in league with witchcraft. One of the most important books on mining during that period called “De Re Metallica”, published in 1556, describes the practice in this excerpt:
There are many great contentions between miners concerning the forked twig, for some say that it is of the greatest use in discovering veins, and others deny it. Some of those who manipulate and use the twig, first cut a fork from a hazel bush with a knife, for this bush they consider more efficacious than any other for revealing the veins, especially if the hazel bush grows above a vein.
Others use a different kind of twig for each metal when they are seeking to discover the veins, for they employ hazel twigs for veins of silver; ash twigs for copper; pitch pine for lead and especially tin, and rods made of iron and steel for gold. All alike grasp the forks of the twig with their hands, clenching their fists, it being necessary that the clenched fingers should be held toward the sky in order that the twig should be raised at that end where the two branches meet. Then they wander hither and thither at random through mountainous regions.
It is said that the moment they place their feet on a vein the twig immediately turns and twists, and so by its action discloses the vein; when they move their feet again and go away from that spot the twig becomes once more immobile.
Nevertheless, these things give rise to the faith among common miners that veins are discovered by the use of twigs, because whilst using these they do accidentally discover some; but it more often happens that they lose their labour, and although they might discover a vein, they become none the less exhausted in digging useless trenches than do the miners who prospect in an unfortunate locality.
Therefore a miner, since we think he ought to be a good and serious man, should not make use of an enchanted twig, because if he is prudent and skilled in the natural signs, he understands that a forked stick is of no use to him, for as I have said before, there are the natural indications of the veins which he can see for himself without the help of twigs.
There are variations on the construction of dowsing rods. The original technique consists of using a forked branch cut from a live tree, any tree will work but sticks from willows, witch hazel, and various fruit and nut trees seem to be the most popular. You grasp the ends of the “Y “in your hands with your palms facing upwards. The technique is to walk around and as you approach the target (ground water, gold deplost, etc) the rod will bend towards the ground.
Modern dowsers prefer to use metal rods. A modern dowsing rod consists of two metal rods created from sixteen inch long steel acetylene welding rods with a 90 degree bend forming a handle on each (also known as L-rods). The latest innovation uses ball bearings in the handle to allow the rod to move freely. The modern divining rods don’t bend towards the ground, the technique is to allow the rods to either cross or reach the operator’s chest or point in certain directions.
There are people claiming to be able to conduct long-range dowsing from distances of 100s of meters up to thousands of kilometers away. Some even claim to be able to dowse using a map from the other side of the world.
Dowsers claim to be able to find all sorts of things ranging from water to gold and even your lost car keys. Dowsing for water is the most common. There are quite a few practitioners of water dowsing that do so as a career. The American Society of Dowsers currently has over 2000 members.
In the summer of 2020 I had the opportunity to try dowsing myself. A friend of mine had some dowsing rods and we gave it a try while exploring his claim. He told me that you need to visualize the thing that you’re looking for. In this case we were exploring for a hidden paleochannel.
I held the rods horizontally so that they were able to move freely and walked in a straight line while keeping the idea of a channel in my head. At one spot I was surprised to feel the rods moving without my control and they did cross in front of me. It was a cool feeling and did seem supernatural. We marked the spot using a pin flag. My friend continued over a larger area and we mapped several spots where he felt the rods cross. The results didn’t match up to our seismic survey but he will be testing the area with his excavator next summer.
My personal account was by no means a conclusive test. It certainly piqued my curiosity though.
I know several professionals that occasionally use the technique to locate underground utilities such as water lines and electrical lines. They swear that it works, they don’t know how or why but swear that it does. Several utility companies in Canada do use divining rods occasionally.
Long Range Locators
There are even electronic devices that claim to extend the dowsing signal for great distances. These devices are called Long Range Locators (LRLs).
There is quite a range of LRLs on the market, they range from devices that look like a ray gun to “signal generators”, “oscillators”, “harmonic molecular resonators”, or other scientific-sounding names. The world of LRLs is very murky. The majority of LRLs are fake and many manufacturers have been charged with fraud.
One such device called the Omni-Range Master retails for $2,885 USD and makes the following claim:
The signal line from the Omni-Range Master can scan an area of at least 64 square miles and determine if any of the sought-after mineral is present within 15 minutes of the start of operation
It also claims to have “Accuracy of 1/32 of an inch from 50 feet to over 8 miles”. Wow, it would be pretty cool if that actually worked!
Credit for the above photo goes to Carl at geotech1.com. He’s done a lot of research and testing on LRLs. Check out his site for some surprises on some of the most popular long-range locator products on the market.
The Omni-Range Master is a favorite among dowsing and LRL enthusiasts even though it doesn’t actually do anything.
The manufacturer supplies a list of frequencies to locate various substances and items such as:
Diamonds – 12.835 Khz
Gold – 3.025 Khz
Titanium – 13.385 Khz
“Prehistoric Rex” bones – 15.367 Khz
Paper money ($100) – 9.41 Khz
Paper money ($20) – 12.77 Khz
It’s interesting that it mentions bones of a non-existent dinosaur which would be made up of a complex mix of molecules. It’s also strange that it has two different frequencies for paper money and that it lists paper money at all.
This device uses a standard waveform generator (chip that produces an electrical current in a variety of voltages and frequencies). You then plug electrodes into the ground and the idea is that the device will induce “molecular resonance” in the surrounding area and create “signal lines” that you can follow with dowsing rods.
The device uses a 12V power supply and does not transmit enough power to do anything productive. I suspect that believers in “signal lines” and LRLs believe that a very low voltage can be amplified by a form of harmonic resonance but there is absolutely zero evidence for that.
At face value, the concept of “frequencies” and electrodes in the ground is similar to some geophysical techniques such as Induced Polarization (IP) and Resistivity that are commonly used. IP uses 25,000 volts and very specialized recording equipment. It also involves a comprehensive data processing technique. IP can detect conductive ore bodies if they are big enough but even that advanced geophysical technique won’t show you exactly where gold is (or dinosaur bones).
Explanations of the Phenomenon
Proponents of the dowsing technique have a variety of explanations of the mechanics behind the phenomena. One person on a prospecting forum recently claimed “The rods simply extend your personal magnetic field..which, in turn responds to, and interacts with vibrational frequencies of the Earth.”
Some claim that there is psychic energy involved while others say it has something to do with the solar cycle and charged particles from the sun. There are just about as many explanations as there are practitioners.
A recently published book, “The Art of Dowsing: Separating Science from Superstition” by Michael Fercik, tried to explain dowsing in scientific terms. Here’s a quote from the book:
The hands-on dowsing practices are absolutely 100 percent correct, but the dowsing theory could be slightly off here or there. I expressed in wording to the best of my abilities on how I can dowse to find sought objects, with the physics that came from electrical classes, a college physics class, educational books, and educational TV programming. If a group of open-minded physicists say one of the theories is not this way but is that way, then I stand corrected, and we go by the group of open-minded physicists’ theory.
The author seems to have a very faint understanding of science despite the fact that his book is titled “Separating Science from Superstition”.
Fercik explains his own theory of the concept of “elemental magnetism”. It’s important to clarify what the word “theory” means in the realm of science. People often claim something is “just a theory” or “I have a theory”. That word has a specific meaning in science. A scientific theory is an explanation of the natural world that makes testable and verifiable predictions. Those predictions must be confirmed by experiments using the scientific method. You can’t have a theory without it being able to make predictions that can be verified by other people, otherwise it’s just a guess and doesn’t have anything to do with science.
Fercik goes on to explain that each element in the periodic table has its own unique “elemental magnetism” and that a dowsing rod can “tune in” to that unique characteristic similar to a radio tuning to a radio station. He claims that you can tune in your rod by attaching a “one-tenth troy ounce” piece of silver, for example. Then your rod is tuned for silver. He emphasizes that it must be 99.999 percent pure silver or gold or else it won’t work.
The author claims that a dowsing rod and metal detector work in similar ways and that the dowsing rod is powered by “human neuron electrical signals”. Apparently walking while dowsing builds up a static charge strong enough to move the rods when your target is close.
Fercik claims that metal detectors and dowsing rods both work by “picking up the unique emitted elemental magnetic flux lines of the targeted element or targeted elemental mass.” In reality neither device works that way.
Metal detectors transmit an electromagnetic field from the search coil and any magnetically susceptible metal objects that are close enough and large enough become energized and retransmit their own field. A second coil receives the field transmitted by the metal objects. It’s a similar concept to electromagnetic geophysics such as HLEM or aerial TEM. Modern metal detectors are able to differentiate certain phase responses and that allows them to discriminate between different metals such as gold and iron. When metals have a similar phase response such as tin foil and gold it’s hard to tell the difference.
The author describes the movement of the dowsing rod as the result of closing a circuit and allowing static electricity to flow. According to the book, when in contact with the sought element’s “elemental magnetic flux lines” a circuit is created and the dowsing rod connects the static electricity of the human body’s nervous system with the “elemental flux density” of the sought element.
The author goes on to introduce numerous other terms related to magnetism that he created from his own imagination. His ideas don’t meet the criteria for a scientific theory, they could be easily tested but there is no evidence of that in the book. He also fails to recognize that water is not made of a single element, it’s composed of hydrogen and oxygen.
The author should have consulted someone with a background in physics or chemistry instead of his emphasis on “educational TV programming”. Scientists aren’t hard to find, however, had he done that there wouldn’t be a book to write since it would have been debunked before it even reached the publisher.
Dowsing rods have been shown to work on the same principle as a Ouiju board. The rods, or the planchette in the case of the Ouija board, are moved by human muscles not ghosts, magic or “elemental magnetic flux lines.” The reason the operator isn’t aware that they are actually moving the object is what’s referred to as the ideomotor effect.
The ideomotor effect was discovered by William Benjamin Carpenter in 1852 and describes the movement of the human body that is not initiated by the conscious mind. Your body moves without requiring conscious decisions all the time. In sports it’s referred to as muscle memory. Driving a car is another example, or playing a musical instrument.
When you are startled or accidentally touch something hot your body is able to move in a way to protect you without conscious input from your brain. Many experiments have shown that under a variety of circumstances, our muscles will behave unconsciously in accordance with an implanted expectation. As this is happening we are not aware that we ourselves are the source of the resulting action.
One of the first people to study this effect was the famous scientist Michael Faraday who also established the basis for the concept of the electromagnetic field in physics among many of his important contributions to the world of science. During the time of Faraday’s ideomotor experiment, in 1853, mysticism was at an all time high and Ouija boards were very popular. He set out to determine what the real force behind the Ouija board was.
Faraday’s experiment was simple. He placed a small stack of cards on top of the Ouija planchette (the piece that you put your hands on). In this experiment, if the force was coming from the participant’s hands the top of the deck of cards would move first. If there was another force the bottom cards would move first. What Faraday and others have shown in every case is that the force was coming from the participant’s hands and not some external entity.
Modern experiments have been done to test dowsing using high-speed cameras. It has been shown that the force on the dowsing rods comes from the person and not from an external force.
It’s interesting that today’s purveyors of the technique insist that testing needs to be done by “open-minded” scientists as if there is some kind of conspiracy against dowsing. There is no conspiracy, in fact there have been a lot of scientific experiments conducted to test the dowsing.
Take a look at some of the studies mentioned below. This is by no means a comprehensive list, there are hundreds of studies on this subject.
Chris French 2007
Psychologist Chris French conducted a double-blind study on dowsing in 2007. The study was filmed as part of a TV show hosted by Richard Dawkins.
Professor French had this to say about the dowsing experts that took part in the study:
I think that they are completely sincere, and that they’re typically very surprised when we run them through a series of trials and actually say, at the end of the day, “Well your performance is no better than we would expect just on the basis of guess work.” And then what typically happens, they’ll make up all kinds of reasons, some might say excuses, as to why they didn’t pass that particular test.
Ongley tested 75 professional water diviners in New Zealand in 1948. The report, linked above, is quite interesting, it discusses some of the history and methods available at the time.
Ongley concluded, “If the seventy-five diviners tested representative of all occupations and from all parts of New Zealand, not one showed the slightest accuracy in any branch of divination. That 90 percent of the diviners are sincere does not lessen the harm that they do.
Vogt, E & Hyman, R, 1959
Water Witching, U. S. A.
Vogt and Hyman argue at some length that anecdotal evidence does not constitute rigorous scientific proof of the effectiveness of dowsing. The authors examined many controlled studies of dowsing for water, and found that none of them showed better than chance results.
Taylor, J. G. & Balanovski, E., 1978
Can electromagnetism account for extra-sensory phenomena?
In this study John Taylor and colleagues conducted a series of experiments designed to detect unusual electromagnetic fields detected by dowsing practitioners. They did not detect any.
Foulkes, R. A, 1971
Experiments organized by the British Army and Ministry of Defence suggest that results obtained by dowsing are no more reliable than a series of guesses.
This study took place in 2012 and studied a different part of the dowsing technique. The study states: “According to the theory of psionic medicine, every living thing and inanimate object is continuously vibrating at a molecular level. This vibration is sensed subconsciously by the dowser, and it is then amplified through the pendulum or other dowsing device.”
Participants were tested on their ability to detect naturopathic medicine vs a placebo in double blind trials. The study showed that the experienced dowsers were not able to identify the correct substance with results better than chance alone.
This study is a review of previous experiments which was put together by the office of the state archaeologist at the University of Iowa. The study concluded:
Simple experiments demonstrate that dowsing wires will cross when the dowser observes something of interest; this is an example of the subconscious ideomotor effect, first described by Carpenter (1852). This does not disprove dowsing, but demonstrates that simpler explanations can account for the phenomena observed by dowsers The premise that dowsing rods cross when exposed to a large magnetic field created by a subsurface anomaly runs contrary to basic scientific understanding of magnetic fields, and does not hold up under simple experiment.
One Million Dollar Paranormal Challenge
The One Million Dollar Paranormal Challenge is an offer by James Randi, a famous magician, to anyone who could demonstrate a supernatural or paranormal ability under agreed-upon scientific testing criteria.
In his book, “Flim-Flam! Psychics, ESP, Unicorns, and Other Delusions”, Randi describes one of the tests that he conducted in 1979 where four dowsers took an attempt at the prize.
The prize in 1979 was $10,000 and he accepted four people to be tested for their dowsing ability in Italy. The conditions were that a 10 meter by 10 meter test area would be used. There would be a water supply and a reservoir just outside the test area. There would be three plastic pipes running underground from the source to the reservoir along different concealed paths. Each pipe would pass through the test area by entering at some point on an edge and exiting at some point on an edge. A pipe would not cross itself but it might cross others. The pipes were 3 centimeters in diameter and were buried 50 centimeters below ground.
Valves would select which of the pipes water was running through, and only one would be selected at a time. At least 5 liters per second of water would flow through the selected pipe. The dowser must first check the area to see if there is any natural water or anything else that would interfere with the test, and that would be marked. Additionally, the dowser must demonstrate that the dowsing reaction works on an exposed pipe with the water running. Then one of the three pipes would be selected randomly for each trial. The dowser would place ten to one hundred pegs in the ground along the path he or she traces as the path of the active pipe. Two-thirds of the pegs placed by the dowser must be within 10 centimeters of the center of the pipe being traced for the trial to be a success. Three trials would be done for the test of each dowser and the dowser must pass two of the three trials to pass the test.
A lawyer was present, in possession of Randi’s $10,000 check. If a claimant were successful, the lawyer would give him the check. If none were successful, the check would be returned to Randi.
All of the dowsers agreed with the conditions of the test and stated that they felt able to perform the test that day and that the water flow was sufficient. Before the test they were asked how sure they were that they would succeed. All said either “99 percent” or “100 percent” certain”. They were asked what they would conclude if the water flow was 90 degrees from what they thought it was and all said that it was impossible. After the test they were asked how confident they were that they had passed the test. Three answered “100 percent” and one answered that he had not completed the test.
When all of the tests were over and the location of the pipes was revealed, none of the dowsers had passed the test. Dr. Borga had placed his markers carefully, but the nearest was a full 8 feet from the water pipe. Borga said, “We are lost”, but within two minutes he started blaming his failure on many things such as sunspots and geomagnetic variables. Two of the dowsers thought they had found natural water before the test started, but disagreed with each other about where it was, as well as with the ones who found no natural water.
Cargo Cult Science
Dowsing has never actually passed any real scientific test. That has nothing to do with how “open minded” the scientists doing the study are. Science does not rely on opinion, it’s simply an unbiased way of testing and explaining the natural world. True science does not try to prove a hypothesis, a real scientist should try their best to disprove the hypothesis and only when all attempts to disprove it have failed can we draw the conclusion that the phenomenon is true.
The famous physicist , Richard Feynman, described this perfectly in his 1974 commencement address to the graduating class of Caltech. It’s a great speech that touches on pseudoscience and cargo cults. Check out the video below.
Dowsing is a pseudoscience, at best, and attempts to explain dowsing would definitely fit into Feynman’s description of Cargo Cult Science.
It would be amazing if a prospector could actually pick up two metal rods and walk around until they find a high-grade gold deposit. The idea is very appealing, and that desire is what has kept it around for so many years. If that actually did work, everyone would be able to find gold in large quantities and the practitioners of dowsing would all be multi-billionaires.
Even if you ignore the scientific studies and everything else mentioned in this article it’s pretty obvious that the practitioners of dowsing have failed the fundamental logic test. If they have the magical ability to find gold by holding two rods, shouldn’t they have tons of gold in their possession?
I have had long conversations with numerous expert dowsers. Except for a few that get paid to dowse for water, they all have a day job and dowse as a hobby. Dowsers all swear that the technique works and is effective but they don’t have any gold to show for it. I have yet to meet a dowser that has discovered billions of dollars worth of gold and lives in a mansion.
It is possible that there is some hidden force that we don’t yet understand that can be tapped into using the human body and two metal rods. That’s the idea promoted by dowsing practitioners. They claim there are unexplained “frequencies”, “harmonic molecular resonance”, “elemental magnetism” or other clever-sounding phrases that science hasn’t yet been able to explain.
Carl Sagan famously stated, “Extraordinary claims require extraordinary evidence.” The claims made by dowsers are certainly extraordinary. The extraordinary evidence has yet to present itself.
If you’re waiting for the discovery of a magical force that presents signal lines to buried gold that only a specialized few are able to pick up on with their innate abilities, I wouldn’t hold your breath. It’s far more likely that the phenomenon of dowsing is little more than a self-delusion brought on by unconscious movements in response to implanted expectations, also known as the ideomotor response.
I’d love to hear your thoughts and personal dowsing stories. Feel free to post them in the comments below.
There’s something about gold. It possesses us, sometimes entire nations to accumulate more and more of it. Humans have had a strong affinity for gold since the times of the ancient Egyptians and the Aztecs. Gold has been used as currency for thousands of years. Wars have been fought for it, entire civilizations slaughtered for their gold. Pindar, the ancient Greek poet, described gold as “a child of Zeus, neither moth or rust devoureth it, but the mind of man is devoured by this supreme possession.”
It’s hard to describe the feeling of finding your first gold nugget in an old stream bed. It sits there in your pan shimmering, the way that only gold can. You immediately recognize it’s power, it is intoxicating. This is what drives prospectors past and present to take great risks in the search for gold. There’s more than just the value of gold that attracts us to it. The word “placer” itself comes from the Spanish word meaning “pleasure”. For some it is an addiction, for others it symbolizes wealth. You’ll be hard pressed to find a member of the human species who wouldn’t be interested in some gold.
Gold has several properties that make it desirable. Most importantly it does not rust or tarnish. Gold artwork discovered in the tombs of Egypt looks just as lustrous today as it did 5000 years ago. Why is that? Gold belongs to a group of metals called the “Noble Metals”. They’re called noble because like nobility in old time monarchies they don’t associate with others. It’s fancy way of saying that the metals don’t readily react. Conversely iron will readily react with oxygen to form iron oxide (aka rust). Gold and other noble metals, such as platinum, possess a very strong atomic structure that requires a lot of energy to disrupt.
The ability to maintain over time is common of all valuable substances. A diamond for example produces a characteristic glow when cut and faceted properly but what good would it be if it disintegrated a month later? Diamonds are extremely hard and have a rock solid crystal structure. Other valuable gemstones all share similar properties, emeralds, rubies, sapphires and garnets all sit at the high end of the hardness scale. While gold isn’t hard in a geological sense it maintains it’s shape and luster indefinitely.
Gold is also very malleable. Meaning that it can be hammered or pressed into various shapes without cracking or losing its consistency. You could stretch an ounce of gold into a wire 80km long or produce a sheet of gold leaf 80 meters by 80 meters wide. Gold is also an excellent conductor. Not quite as good as copper but a better conductor than nickel, brass, iron, tin, and aluminium. Gold conductive wire is used in many critical electronics applications such as computer motherboards, smart phones and satellites.
What really makes gold valuable though is it’s scarcity at the earth’s surface. Approximately 165,000 metric tons of gold have been produced in the entirety of human history. While that may sound like a lot the amount of gold produced by mining is extremely small in comparison to other metals. For example the Carajás Mine in Brazil produces an average of 300 million metric tons of iron per year and has a deposit estimated at 7.2 billion metric tons. And that’s just one mine. All the gold ever produced would fit inside one Olympic sized swimming pool.
It is often stated that you can’t eat gold. While that’s not entirely true, (see gold covered pizza) an all gold diet wouldn’t provide much nutrition, and you’d probably have some digestive issues. The yellow metal doesn’t appeal to our basic needs for survival but neither does money or a smartphone. That doesn’t make any of these things less valuable.
We typically think of value in dollar terms. When evaluating an investment such as stocks or real estate it’s hard to think of anything else. Dollars are not constant though, they are subject to manipulation and inflation. For at least 6000 years gold has been used as currency and unlike modern currency is not subject to inflation. Modern currencies are what is called “Fiat Currency”. There is no standard on what a modern currency note can be exchanged for. Their value relies solely on people’s faith in it. Or more correctly their faith in the government. Inflation rates can severely affect the spending power of a dollar. There are countless examples, the most striking is the inflation of the German Reichsmark which rose from 4.2 marks to USD in 1914 to a peak of around 4.2 trillion marks to the US dollar by November 1923. At that time a wheelbarrow full of German marks wouldn’t even buy a newspaper.
Historically world currencies were backed by the gold standard which meant that by law any amount of paper money could be exchanged for a specified amount of gold. In the 1920s each US dollar was backed by 1.5 grams of gold. The dropping of the gold standard in Germany during WWI allowed for the hyperinflation that followed. The United States dropped the standard during the great depression to avoid the federal gold supply from being completely depleted. Canada followed suit in 1933. There’s much debate on the merits of dropping the gold standard. What resulted though is the ability for the government to completely control the currency without requiring tangible assets (ie. gold) to back it up.
So if the dollar is backed by nothing and can be manipulated at will how do you gauge the value of gold. Or anything for that matter. True value depends on what people are willing to trade for your goods. Money makes it easy to barter and trade goods since it’s ubiquitous and there is an agreed upon value at any given time. For example if you want to sell your car on craigslist you’ll have an idea of how many dollars you want for it. Lets say you have a used Honda Civic. You could sell that easily for $4000 CAD. That same Honda Civic could be traded for a 1 carat diamond engagement ring. 50 years from now a used car might sell for $25,000 dollars due to inflation but the exchange rate of car to diamond ring would remain the same.
The old adage that an ounce of gold will buy you a nice suit still rings true today. In the gold rush era (1848-1900) an ounce of gold would trade for about $20 USD, and would also buy a nice suit. A typical suit today would cost you about $450 USD. So it would seem that today’s gold would buy you 3.5 nice suits. You have to consider that in the 1800s nice clothing was not mass produced. To compare accurately you’d have to look at a tailored suit. A mid range tailored suit made in the United States costs between $1650 and $1800 today. At present gold is trading at about $1250 USD so the suit adage falls just above the quoted dollar value of gold.
What really gives gold it’s value is the cost of exploration and production. Being very rare it takes a lot of effort to find gold. Once it’s found it is expensive to produce as well. For example Barrick’s Cortez mine in Nevada has an average grade of 2.11 grams per ton. That means that for every ton of ore processed they average 2.11 grams of gold. Barrick’s published production cost at the Cortez mine is about $900/oz. It really is remarkable that they can move and process the 15 tons of rock required to obtain an ounce of gold for $900.
The cost of producing an ounce of gold varies for each mine. In a placer operation it is a constant cat and mouse game to keep costs low enough to make production economical. When gold commodity prices fall below production costs mines shut down and less and less gold is produced. The production cost, driven by scarcity is the single most important factor that drives the price of gold.
Gold exploration is also very expensive. In the times of the North American gold rush placer and hard rock gold was discovered all over the Western part of the continent. From the 1840s to 1900 new gold districts were popping up every year as discoveries were made. Trending almost in sequence Northward from California to the Yukon as explorers made their way through the wilderness. In more modern times most of the easily reachable areas have have been at least partially explored. Exploration today mostly takes place in more and more remote areas, such as the Canadian Arctic or other places with a small human footprint.
To properly explore a claim in these areas requires a camp. helicopters and all kinds of equipment. A typical small exploration program in the Northwest Territories can cost well over $1,000,000 per season with slim chances of success. While advancements in exploration technology such as geophysics and aerial imagery can provide information that wasn’t available to previous explorers there is no silver bullet.
The costs of thousands of exploration ventures that didn’t amount to a mine are factored into the price of gold as well. For the estimated 100,000 explorers that took part in the Yukon gold rush only a select few managed to recoup their costs. Some made made great discoveries but many more spent their life savings on an adventure but returned with no gold.
Gold’s value is based on it’s unique properties, people’s desire for the very special metal and the work required to find and produce it. The value has nothing to do with the the dollar value attached to it. For every ounce of gold produced tons of rock had to be excavated, the deposit had to be discovered and mapped, and the ore milled and smelted to extract the gold. As you gaze upon your gold ring and admire it’s beauty think about the story that it could tell you.
Mining under Earth’s oceans is just starting to happen. We have gotten pretty good at mining deposits that are accessible by land but 71% of the Earth’s surface is covered by water. To date no large scale mining operation has succeed under the ocean which means that it’s all virgin ground.
Amazingly the human race has spent more time and money exploring outer space than we have under our own oceans. Over 500 people have been to space while only three have ventured to the deepest part of the ocean, the Mariana Trench. We have better maps of the surface of Mars than the bottom of the ocean, although the ocean maps are pretty cool.
The same geological processes that happen on land also take place under the ocean. There are volcanoes, mountain chains, faults and earthquakes. All the same types of mineral deposits occur under the ocean such as epithermal gold, porphyry, and placer. There are also diamond pipes, massive sulphides and everything else that we mine at the surface.
The ocean also has types of deposits that we can’t find on land. One special mineral deposit is called Polymetallic Nodules. These are concretions of metallic minerals that occur under the ocean. The nodules grow sort of like stalactites do in a cave, over time layers of metallic minerals precipitate out of seawater and add to the nodule. The growth of nodules is one of the slowest known geological processes taking place at a rate of one centimetre over several million years.
Polymetallic nodules are roughly the size and shape of a potato and contain primarily manganese as well as nickel, copper, cobalt and iron. They can be found on the sea floor or buried in the sediment. Nodules can technically occur anywhere in the ocean but seem to be in greatest abundance on the abyssal planes around 5000m deep. Nodule mining would be similar to placer gold mining except under water.
Anouther resource that is unique to the ocean floor is Ferromanganese Crusts. These are similar to nodules but occur as a coating on other rocks. These crusts can be found all over the ocean with thicknesses ranging from 1mm to 26cm. Ferromanganese crusts typically occur in the vicinity of underwater volcanoes called seamounts or near hydrothermal vents. Crusts with mineral grades that are of economic interest are commonly found at depths between 800m and 2500m.
Ferromanganese crusts are composed primarily of iron and manganese, hence the name. Typical concentrations are about 18% iron and 21% manganese. Cobalt, Nickel and Copper occur in significant quantities as well. Rare earth metals such as Tellurium and Yttrium can be found in metallic crusts at much higher concentrations than can be found on the surface. Tellurium is used in solar panels and is quite valuable.
Sea-floor massive sulphides (SMS) are a younger version of volcanic massive sulphides (VMS). The two deposits are similar except that VMS are typically ancient and SMS are currently forming. SMS deposits occur where superheated hydrothermal fluids are expelled into the ocean. They typically form around black smokers near continental rift zones. SMS are know to hold economic concentrations of Gold, Copper, Silver, Lead, Nickel and Zinc.
Black smokers create SMS deposits by expelling superheated sea water that is rich in metallic elements. Cold sea water is forced through the sea floor by the pressure created from the weight of the water column above it. The water is then heated to temperatures in excess of 600°C when it is brought close to the magma that lies below. The heated water becomes acitic and carries with it a high concentration of metals pulled from the surrounding rocks. Once the hot, metal rich, water comes into contact with cold sea water the metals crystallize and deposit on and around the black smoker.
Large scale ocean floor mining has not taken off yet. Attempts have been made since the 1960s and 70s but failed due to technological and financial challenges. Small scale shallow ocean mining has been a lot more succesful in recent years. A great example is the popular TV show Bering Sea Gold. The miners in Nome Alaska are using modified suction dredges to comb the sea floor in shallow waters.
Currently proposed sea floor mining ideas are essentially super high-tech placer mining. They involve ways to dig through the surface layers of the ocean floor, bring the material to the surface and ship it to a processing facility. Its a lot like dredging but on a massive scale. As mentioned above, normal hard rock deposits also occur under the ocean but no plans have been proposed to build open pit mines under the ocean. That would involve all the challenges of building a mine on land with the added complexity of operating under the ocean.
Why is ocean floor mining possible now when it wasn’t 20 years ago? The answer comes down to one word, robots. The world of under water mining is the domain of autonomous drones and human controlled ROVs. Robot submarines are nothing new, they have been around since the 70s and have been used to explore depths of the ocean that are very difficult for humans to get to. UUVs or unmanned underwater vehicles are a little bit newer, they are basically an autonomous version of ROVs. Ocean mining robots have just been invented and share a lot of the technology used in these devices and they look like something straight out of science fiction.
The first deep sea mining project is currently being developed off the coast of Papua New Guinea. The project is called Solwara 1 and is being developed by a Vancouver BC mining company called Nautilus Minerals. Solwara 1 is a copper/gold SMS deposit with estimated copper grades of 7% and gold grades in excess of 20g/t and an average gold grade of 6g/t. The property sits at about 1600m depth.
Nautilus has developed a suite of underwater mining robots and a complete system to mine the precious metal and bring it to shore. There will be the bulk cutter pictured above, an auxiliary and a collection machine. Please take a moment and marvel at these amazing achievements of engineering.
After the robots dig up and collect the ore a custom designed Riser and Lift System (RLS) will bring the material to a giant ship that acts as the mine control center dubbed the Production Support Vessel (PSV). The RLS is basically the world’s most powerful suction dredge. It’s pretty complex, this is the description on the Nautilus Minerals website:
The Riser and Lifting System (RALS) is designed to lift the mineralised material to the Production Support Vessel (PSV) using a Subsea Slurry Lift Pump (SSLP) and a vertical riser system. The seawater/rock is delivered into the SSLP at the base of the riser, where it is pumped to the surface via a gravity tensioned riser suspended from the PSV.
Once aboard the Production Support Vessel the mined slurry will be dewatered and stored until anouther ship comes to take the material on shore for processing. The removed sea water is pumped back down the RALS which adds hydraulic power to the system. Pretty cool stuff! Check out the video below for an visual explanation of how it will all work.
Ocean floor prospecting is not a good place to be gold panning or hiking around with a rock hammer. It is also difficult to take usable photos due to poor light and lots of debris in the water. So how do you explore for minerals in the ocean? Geophysics and robots.
Geophysical exploration is not unique to the ocean. The same techniques are used routinely on land to find every type of mineral deposit. Ocean geophysics is also not new. The main workhorse of mining exploration is magnetometry. Which means mapping changes in earth’s magnetic field using a specialized sensor. The technique was actually developed to detect enemy submarines during World War II. Since then magnetometers and the science behind them have evolved into accurate tools to measure geology.
I’m using a proton precession magnetometer in the photo below. There is some sample magnetometer data on the left. Mag maps look similar to a thermal image except the colour scale represents magnetic field changes (measured in nanoTesla) instead of temperature.
Magnetometers are excellent tools for ocean mining exploration. They are not affected by the water and are excellent at detecting metallic anomalies. There are now underwater drones that can collect ocean magnetometer surveys without the need for human intervention.
Other geophysical techniques have been used in ocean mineral exploration. Electomagnetics (EM) techniques are also great tools for exploration under water. EM works in a similar way to magnetometry except that they emit their own source. Conventional metal detectors are actually a small version of an EM system. While mag passively measures Earth’s magnetic field EM measures the difference between a source and received pulse. EM also works great for discovering metallic anomalies and is being incorporated into autonomous drones as well.
There are other types of ocean geophysics such as seismic refraction which uses a giant air gun to send a sound wave deep into the crust and measures the response on floating hydrophones. Sonar and other forms of bathymetry can provide detailed maps of the ocean floor. Bathymetry techniques can create imagery similar to LiDAR that is used on land.
Ocean mining is just in its infancy and some really cool technology is being used. Advancements in the robotics have allowed mining and exploration to be completed without a person having into enter the water. As technology advances further we will be able to explore vast areas of the ocean floor and discover immense mineral reserves that are presently unknown. It is estimated that we have only explored about 5% of the ocean floor, who knows what we’ll find down there?
Back in 2010 I had the opportunity to work on a diamond exportation program in the Canadian Arctic. The camp was called Credit Lake and was located near Lac de Gras in the North West Territories. The Lac de Gras region was the epicentre of the 1990s diamond rush after the discovery of the Point Lake kimberlite pipe by Chuck Fipke. Today there are three operating diamond mines in the region Diavik, Ekati, and Snap Lake.
Diamonds are found in volcanic structures that are called kimberlite pipes. These are volcanic events that take place very rapidly. Most volcanoes take thousands or millions of years to develop. A volcanic pipe can develop and explode in less than a day. These volcanic explosions are charged by high pressure carbon dioxide and water vapour. And travel from the below the crust melting through rock at over 100km/h.
It is important that volcanic pipe events happen quickly if you want to mine diamonds. The environment where diamonds form is under intense heat and pressure. Once the pressure is removed diamonds will melt into graphite which is much less desirable. In kimberlite pipes diamonds are carried to the surface as the superheated kimberlite melts its way through the layers of the crust. When the pipe reaches the surface it releases its energy in a huge explosion and then quickly cools. The diamond crystals do not have time to melt, they cool with the rest of the pipe and stay in place.
The volcanic events that created the North West Territory kimberlite pipes took place millions of years ago. The surface has been subjected to many ice ages over the years and different continental ice sheets have scoured the surface like a bulldozer. To find a pipe today you look for the debris field left behind as the top of the pipe was scraped by ice sheets. As the glacial ice sheets retreated they left behind a trail of ground up rock and indicators for diamonds if you’re lucky.
My first stint at the camp was for six weeks in 2010. We were searching for diamonds as well as nickel. My role was to analyze pulverized rock samples from an R/C drill as well as preparing samples for assay and general exploration work. I returned in 2013 to conduct geophysical surveys including ground (snowshoe) magnetometer and HLEM. Both trips were in early spring when the temperature in the Arctic ranges from -50°C to -10°C. Show storms were frequent and the ice on the lake was five feet thick.
The camp is extremely remote, approximately 300km North of Yellowknife,NWT. Everything is brought in by ski plane or helicopter. In addition to exploration work we had to work together to keep the camp running. When a plane would arrive we would all pitch in to get the groceries, diesel drums, and any other supplies off the plane and into the camp. The same was true for getting water out of the frozen lake for showers, laundry and the kitchen. Water is always a challenge in remote areas when it is extremely cold.
While I was at the camp we experimented with several different water gathering techniques they all had their merits. What we ended up doing was using a chainsaw to cut out a section of the lake ice. Then used an ice auger to drill the final few feet (see video above). We used a snowmobile toboggan to transport pails up to the reservoir inside the kitchen.
To travel to and from the locations we were exploring we took a helicopter. We had a Eurocopter Astar B3 to shuttle people and move the heli-portable drill around. We also had a couple of snowmobiles and a GMC pickup truck that had tracks instead of wheels.
The RC drill is a super light weight drill that produces crushed rock instead of core. The RC stands for Reverse Circulation. The drill is air powered and behaves like a giant hammer drill, like the kind that you use for masonry work. The air returns from the bit carrying the rock chips to a hopper where samples can be collected. The advantage of an RC drill is that it doesn’t require water and breaks down for rapid transport. RC drilling is quicker and less expensive than diamond drilling.
After field samples were collected I conducted several tests on them inside our field lab. We had an X-ray fluorescence (XRF) analyzer which is a pretty cool instrument. It bombards the sample with high energy X-ray radiation and the atoms re-emit photons which gives information about their structure. XRF basically gives you a rapid geochemical assay. I also conducted magnetic susceptibility tests and identified the lithology of chip samples using a microscope.
The accommodations were first class. At least as far as small remote exploration camps go. We stayed in Weatherhaven dome tents which are heated by diesel stoves. As long as there is fuel in the stove you will be comfortable in any weather conditions. The stoves are prone to issues though and use half a drum of diesel per day when its super cold. Our beds are constructed out of 2×4 lumber that was flown in and everybody uses a sleeping bag for bedding. This camp was not a “dry camp” which means that alcohol was allowed. That is a huge plus when you’re stuck in the middle of nowhere for six weeks.
The high latitude makes for great northern lights viewing. That is actually my favourite thing about the Arctic. Interestingly the mechanism behind the glow of the Aurora Borealis is the same as the XRF machine. The molecules in the upper atmosphere are excited by a stream of radiation from the sun called the solar wind. When molecules are excited they reach an unstable electron configuration and rapidly release a photon as they return to a stable state. The different colours are due to different molecules being excited such as high altitude ozone, oxygen and nitrogen. The phenomenon is difficult to photograph but here are some of my best shots below. The best photo in the world doesn’t compare to seeing it in real life though.
The days out in the field can be pretty tough when the temperature drops. We built a survival shack that would travel with the drill. Other than that we were fully exposed until the helicopter arrived at the end of the day. The survival shack also made a great place to have lunch out of the wind.
In addition to drill sampling I conducted geophysical surveys to identify kimberlite pipes. We used two types of geophysical survey, magnetometer and HLEM. Magnetometer or “Walk Mag” is a sensor that measures changes in Earth’s magnetic field in very high precision. As you pass over different kinds of rock the sensor will record minute changes in the magnetic field. Once the survey is complete you can produce a map that looks like a topo map except that the you are showing magnetic field instead of elevation. Click here for a sample of a magnetometer map. Kimberlite pipes stick out as an anomaly because they have a different magnetic signature to the surrounding rock. You have to use the old school snow shoes because any metal will mess up the readings.
HLEM (Horizontal Loop Electomagnetic) works in a similar way except that there are two parts to the system. One provides a source field and charges up ore bodies. The receiver records the response signal from the rock. HLEM actually works the same way as a metal detector just on a larger scale and records actual data. The instrument is from the 1980s and is very uncomfortable, fortunately in the winter you are wearing lots of clothes.
I have always enjoyed working in the Arctic. Its not for everyone though. It is insanely cold in the winter and the summer has a lot of bugs. The wildlife is breathtaking I have seen Muskox, Wolverines, Caribou, different coloured bears, Narwhals, and other wildlife that you cannot see below the Arctic Circle. The Northern Lights shows are simply amazing. The people are different too. This kind of work attracts a different breed, those who are willing to travel to remote areas. Arctic explorers all share a strong sense of adventure.