Finding Placer Gold in Ontario

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A Field Guide on Placer Gold for Hobby Prospectors

 

Ontario has long attracted prospectors searching for mineral wealth. The province is internationally known for its hard-rock mining in the Canadian Shield, where major deposits of gold, silver, nickel, and copper have been mined for more than a century. Yet beyond the underground mines and rusty gossans that mark mineralized bedrock lies another fascinating and often overlooked part of Ontario’s geology—placer deposits. These natural concentrations of heavy minerals form when water or glacial activity erodes gold and other durable minerals from their original bedrock sources. The debris is later deposited in sands and gravels of fossil glacial features. For modern rockhounds, gold panners, and hobby prospectors, Ontario’s placer deposits offer a chance to search for gold, and indicator minerals in the province’s rivers and glacial sediments. If finding placer gold in Ontario intrigues you, learn how past glaciers can bring you success.

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Now I must be straight with you, Dark Star Crystal Mines does not offer gold panning tours. Mark just called me to say that our gold articles give that impression - sorry - no. I suppose there has been a big resurgence in gold interest, the price is through the roof and as Mark says, everyone is watching "Gold panning Australia" and seeing these guys dredge up nuggets as big as eggs - thats Australia. Australia is estimated to have 12,000 tons of gold still in the ground, Canada only has 3200 tons still estimated to be in the ground.

 

I do not doubt that there is an enormous amount of gold and gems in Canada's glacial sediment, but its not just lying there for the taking. All the points must align. You find a hard rock gold bearing area, you trace the past flow of the ice sheets, you spot the resulting eskers and rivers running through the eskers. If you are fortunate gold might be in those secret spots in the river that prospectors never share. So my appologies to those of you who called Mark for a tour. We do crystal digs not gold tours. Gold is something of interest to rockhounds in general so it appears here as an article. Oddly rockhounds who are into gold are a niche group. Few seem to stray off in the direction of crystals, but that's our niche at Dark star. We book crystal digging opportunities and what you find at Dark Star is as amazing to us as nuggets are to the "Gold Niche".

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The largest placer-style gold recoveries in Ontario occurred in the Abitibi region, particularly around Lake Abitibi and the lowlands near the Ontario–Quebec border. I'd say to begin your search, head north to the gold bearing regions. You won't find gold in Collingwood, nor crystals on Center Island.

 

During the early 1900s, prospectors working the Abitibi area recovered fine placer gold from glacial out-wash gravels, eskers, and river sediments draining the Abitibi greenstone belt, one of Canada’s richest gold-producing geological regions. Although these placer deposits were never large by global standards, several small operations reportedly recovered hundreds of ounces of fine gold, mostly in the form of flakes rather than nuggets. And then there was the Eldorado discovery where thousands of ounces were found in a cavity with one nugget as big as a butternut.

 

While Ontario seems not to contain the large commercial placer fields found in places like the Yukon or California, placer gold and diamond indicator minerals can still be found in Ontario. During the last Ice Age, glaciers eroded gold from its original hard-rock sources and spread it across the landscape within tills, eskers, and ancient melt water channels. As a result, understanding Ontario’s glacial geology, ice-flow directions, and former melt water systems are one of the most important skills for anyone interested in finding placer gold in Ontario. By learning how glaciers shaped the province’s terrain and where sediments were naturally sorted and concentrated, prospectors can greatly improve their chances of discovering these deposits.

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Table of Contents

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• A Field Guide on Placer Gold for Hobby Prospectors

• Gold Sources in Ontario

• How Glaciers Shaped Placer Gold Distribution in Ontario

• Understanding Eskers: Ancient Rivers Beneath the Ice

• How Placer Deposits Form

• Buried Pre-glacial River

• How Far Do Glaciers Transport Minerals?

• Float is key to finding Placer Gold in Ontario

• Float Tracing Techniques for Prospectors

• Ice Flow Direction in Ontario

• What Happened When the Glacier Melted

• How do Eskers Form at the Front of Ice Flows?

• Why Glacial Geology is key to finding Placer gold

• How to Determine the Direction of Ice Flow When Prospecting in Ontario

• Step-by-Step Method for Tracing Mineralized Float in Ontario

• Why Float Tracing Works for Finding Placer Gold in Ontario

• How Placer Gold Forms in Ontario

• Heavy Minerals Associated with Placer Gold in Ontario

• Heavy Minerals Associated with Placer Gold: Regional Comparison

• Why Quartz Is Often Absent from Placer Gold Deposits

• Eskers: Natural Concentrators of Gold and Heavy Minerals

• What are some Gold Bearing Eskers in Ontario?

• Example of Esker Sedimentation: The Frankford–Marlbank Esker

• How to Prospect an Esker for Gold and Heavy Minerals

• Why Is It So Hard to Find Kimberlite Pipes?

• How does Kimberlite Weather?

• Kimberlite Indicator Minerals

• Indicator Mineral Transport

• Diamonds Found in Glacial Drift Around the Great Lakes

• Canadian Diamonds Found in U.S. States

• Diamond Discoveries in Ontario

• Diamonds and Indicator Minerals in the Wawa Region

• FAQ: Ontario Placer Gold and Diamond Prospecting

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Gold Sources in Ontario

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The Canadian Shield and Bancroft Region

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The Bancroft area contains known occurrences of placer gold, although they are generally small and not mined commercially. Bancroft lies within the Canadian Shield and sits atop very ancient Precambrian rocks including granites, metavolcanic rocks, and greenstone formations.

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These rocks can contain gold-bearing quartz veins that act as the original source of placer gold found in nearby streams and glacial sediments.

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Small quantities of gold have been reported from areas around Spruce Lake and along the York River near Bancroft. The gold is typically extremely fine, often appearing as flour gold. Streams that cut through eskers or glacial gravel deposits in the region can occasionally concentrate these tiny flakes.

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​In the Canadian Shield, gold is most commonly found in certain rock types, particularly within greenstone belts, which are metamorphosed volcanic and sedimentary sequences including basalts, andesites, rhyolites, tuffs, and interlayered sedimentary rocks such as banded iron formations (BIFs). These rocks often host gold in quartz veins, sulfide-rich zones, and shear zones, making belts like the Abitibi, Wawa–Michipicoten, and Timmins areas some of the richest gold-bearing regions in Ontario.

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Gold is also found in metasedimentary rocks such as greywacke, schist, and iron formations, where hydrothermal fluids deposited gold along faults and fractures. Less commonly, granitoid intrusions like granite, granodiorite, and tonalite can host gold, usually along shear zones or late-stage hydrothermal veins, often near greenstone belts. Across these rock types, gold is typically associated with sulfide minerals such as pyrite, pyrrhotite, arsenopyrite, and chalcopyrite, which form lodes and veins that may later contribute to placer deposits. Overall, mafic to intermediate volcanic rocks within greenstone belts are the most consistently gold-rich in the Canadian Shield.

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Where did all the gold go?

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Ontario and California both had enormous gold endowments in the late 1800s. California was estimated to hold roughly 118 million ounces of gold, while Ontario's rock was believed to contain around 200 million ounces. Over the following century and a half, California yielded an extraordinary amount of placer gold—about 68 million ounces recovered from rivers and ancient buried channels. In contrast, Ontario has produced only a few thousand ounces of placer gold, despite its larger overall gold endowment.

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Both regions have experienced long periods of erosion capable of releasing gold from bedrock deposits. Under normal conditions, erosion of gold-bearing rocks should gradually liberate gold into streams where it accumulates in placer deposits. California clearly followed this pattern: erosion of the gold-bearing veins of the Sierra Nevada supplied large quantities of gold to rivers, which then concentrated it in stream gravels and ancient paleo-channels that were later mined.

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Ontario, however, followed a very different geological path. Much of the province was repeatedly covered by continental ice sheets during the Ice Ages. These glaciers did not simply erode bedrock; they scraped, transported, and redistributed sediments across vast distances, mixing gold into glacial till and burying former landscapes beneath thick layers of drift. Ancient river systems were often filled or sealed beneath these deposits, creating fossil valleys and buried channels that are difficult to detect from the surface.

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Because of this glacial reworking, much of the gold released by erosion in Ontario may not have formed obvious modern placer deposits. Instead, it may be dispersed through glacial sediments or concentrated within buried paleo-channels beneath the drift cover. The fact that California has produced roughly 6,800 times more placer gold than Ontario, despite Ontario’s larger gold endowment, suggests that significant quantities of placer gold in Ontario may remain undiscovered. Rather than being absent, the gold may simply be hidden—trapped within glacial deposits or buried ancient drainage systems that have yet to be properly explored.

 

In this sense, Ontario may represent a geological puzzle: a gold-rich province where the processes of glaciation have obscured the natural pathways by which placer deposits normally become visible. Discovering where that redistributed gold ultimately accumulated—whether in buried channels, glacial concentrations, or reworked post-glacial streams—remains one of the more intriguing unanswered questions for prospectors and geologists.

 

Ontario’s Richest Gold Province: The Abitibi Greenstone Belt

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The most gold-rich geological province in Ontario is the Abitibi Greenstone Belt, stretching across northeastern Ontario and into western Quebec.

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Major Gold Districts

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The belt hosts several world-class gold districts including:

• Timmins

• Kirkland Lake

• Red Lake

The Red Lake district is especially famous. Two mines—the Campbell Mine and Red Lake Mine—exploited the Campbell–Red Lake ore body, one of the richest gold deposits ever discovered.

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High-Grade Lode Gold Deposits (Campbell–Red Lake ore body)

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The ore from this system averaged roughly 22 grams of gold per tonne, far richer than most gold deposits worldwide. Gold found in this type of bedrock vein system is known as lode gold.

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Many of these deposits occur along faults and shear zones, often marked by rust-colored weathered rock called gossan, which can signal mineralization below.

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How Glaciers Shaped Placer Gold Distribution in Ontario

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The Influence of the Ice Age

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During the last Ice Age, massive glaciers covered most of Ontario. As these ice sheets advanced, they scraped the landscape and eroded exposed bedrock deposits.

 

Gold and other minerals were incorporated into the ice and carried southward. When the glaciers melted about 14,000 years ago, they deposited this material across the province.

 

As a result, gold can now occur in:

• Eskers

• Moraines and drumlins

• Outwash plains

• Stream gravels

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Modern waterways draining ancient greenstone belts may also re-concentrate this material. Fine flakes of gold—often called “colours”—can accumulate in gravel bars, bends in streams, and natural riffles where heavy minerals settle.

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Why Ontario Has Few Large Placer Deposits

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Despite Ontario’s rich bedrock gold sources, large placer deposits are rare. This is largely due to glaciation.

Ice sheets scoured the landscape, sometimes removing tens to hundreds of metres of rock, destroying older placer deposits and mixing them into unsorted glacial sediments such as moraines.

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For this reason, better placer concentrations tend to form where water has reworked glacial sediments, separating heavy minerals from lighter material.

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The key is finding areas where gold has been naturally concentrated rather than widely dispersed.

 

Understanding Eskers: Ancient Rivers Beneath the Ice

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What Are Eskers?

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Eskers are long winding ridges of sand and gravel formed by rivers flowing beneath or within glaciers.

During periods of heavy melting near the end of the Ice Age, large meltwater rivers flowed through tunnels inside the ice sheet. These rivers deposited gravel and sand along their channels.

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When the ice melted away, the river beds remained as raised ridges across the landscape.

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Why Eskers Matter for Prospectors

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Eskers are important because flowing water sorted the sediments, separating heavy minerals from lighter material.

 

This means eskers may contain:

• Gold particles

• Heavy mineral concentrates

• Diamond indicator minerals

 

Unlike moraines, which consist of unsorted glacial debris, eskers contain cleaner gravel deposits, making them attractive targets for small-scale prospecting.

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Major Esker Systems in Ontario

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Some eskers in Ontario extend remarkable distances. In northern Ontario, individual eskers may run 50 to 150 kilometers, and some connected systems extend even farther. One notable example is the Munro Esker near Timmins, which stretches for more than 200 kilometres across northeastern Ontario.

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How Placer Deposits Form

 

Natural Concentration of Heavy Minerals

 

Placer deposits form when heavy minerals become concentrated in sand and gravel through natural processes such as flowing water or glacial movement.

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Gold is especially prone to concentration because of its high density. Diamonds themselves are not particularly heavy, but the minerals associated with them often are.

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Important diamond indicator minerals include:

• Garnet

• Chromite

• Ilmenite

• Chrome diopside

 

Because these minerals are heavy, they may concentrate in stream gravels and glacial deposits, providing clues that diamond-bearing rocks may exist nearby.

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Why are Indicator Minerals Important?

 

Indicator minerals help prospectors determine whether valuable deposits may exist upstream or up-ice from where the minerals are found.

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Finding such minerals does not guarantee diamonds or gold, but it suggests the geological conditions are favorable.

 

Buried Pre-glacial Rivers

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Ancient Rivers Hidden Beneath Glacial Sediments

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Some of the most intriguing exploration targets in Ontario are buried pre-glacial river channels.

Before the Ice Age, rivers flowed across landscapes that were very different from today. When glaciers advanced, many valleys were filled with sand, gravel, and glacial sediments.

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These buried channels are invisible at the surface but can be detected using:

• Drilling

• Geophysical surveys

• Geological mapping

 

In some areas, these channels may be more than 100 feet deep.

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Examples of Buried Channels in Ontario

 

Several well-known buried river systems exist in Ontario.

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St. David’s Gorge (Niagara Region)

 

Before glaciation, a deep river valley existed near Niagara Falls. During the Ice Age this valley was filled with hundreds of feet of sediment. Engineers encountered the buried gorge while constructing early hydroelectric tunnels. Having been buried by the glaciers this canyon might harbor huge placer deposits built up during the province's pre-history. Much as they are deeply buried, these pre-glacial canyonds might be the key to finding placer gold and diamonds in Ontario.

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The Laurentian and Erigan Rivers

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Before the Great Lakes formed:

• The Laurentian River drained eastward through what is now the Lake Ontario basin.

• The Erigan River flowed through the region now occupied by Lake Erie.

Glaciation later reshaped these landscapes and buried much of the ancient drainage.

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The Newmarket Buried Channel

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One of the largest buried channels lies beneath the Oak Ridges Moraine north of Toronto.

The Newmarket Buried Channel extends for over 100 kilometers and reaches depths exceeding 200 meters in places. Today it contains important groundwater aquifers formed by melt water deposits.​

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The buried paleochannels of the Abitibi–Timmins area 

 

The area around Timmins within the Abitibi Greenstone Belt is widely regarded by geologists as the best place in Ontario for buried placer channels.

Why this area is favorable:

• One of the richest gold regions in the world

• Numerous large lode deposits (e.g., Porcupine Gold Camp)

• Ancient river systems existed before Pleistocene glaciation

• Glaciers later buried valleys under till and glaciolacustrine clay

 

Why Buried Channels Interest Prospectors

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Because these ancient rivers existed before glaciation, they may have had more time to concentrate placer minerals such as gold. Although little exploration has occurred so far, buried channels remain intriguing targets for geological research. 

 

Buried river channels in Ontario are often compared to those in Sri Lanka because both regions contain ancient river systems that were later buried and preserved beneath younger sediments, creating environments that can trap heavy minerals such as gold and gemstones. Despite being on different continents, several geological processes make these buried channels surprisingly similar.

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In both Ontario and Sri Lanka, older river systems formed when landscapes and climates were different from today. Over time these rivers either changed course, were filled with sediment, or were buried by other geological processes.

• In Ontario, many channels were buried by glacial deposits during the last Ice Ages. Thick layers of till, sand, and gravel left by continental glaciers can hide older river valleys beneath the surface.

• In Sri Lanka, the channels were commonly buried by tropical weathering products and younger alluvial sediments as rivers migrated across the landscape.

In both places, the result is an ancient river valley sealed beneath younger materials, preserving the original gravel bed where heavy minerals settled.

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How Far Do Glaciers Transport Minerals?

 

Long-Distance Transport

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Large continental ice sheets can transport rock fragments hundreds of kilometres. It is usually the larger erratic that people see and marvel as to their far-away origins. Numerous erratics along the Niagara Escarpment are composed of  granite from Northern Ontario, marking the path of the Laurentide Ice Sheet and often standing out on flat agricultural land as natural landmarks. Within the vein dykes of the Dark Star claim rockhounds are forever lifting large rounded cobbles from the trenches. Clearly they were moved and dumped there during the last ice age.

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Fast-moving ice streams within the glacier acted like conveyor belts, transporting sediment long distances. The ice itself was not so quick to move boulders as were the rivers entrained and beneath the ice flow. Prospecting these sub glacial streams is key to finding placer gold in Ontario.

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Local Transport Is More Common

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Despite some spectacular long-distance transport, studies show that most glacial sediments are local in origin.

Research in southern Ontario found that most pebbles in glacial gravels came from nearby bedrock sources. Similar results were found in sampling around the Kirkland Lake gold district.

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Gold particles were commonly detected within 2,000 feet of their source, but were usually absent beyond 10,000 feet.

For hobby prospectors, this is encouraging. Finding gold flakes in a stream may mean the bedrock source is relatively close.

Eskers typically formed in segments, each fed by meltwater draining from only a short distance behind the ice margin. As the glacier retreated, new segments formed farther back.

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This means sediments in a given section of an esker were usually derived from a relatively small drainage area, often within about five miles.

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Float is key to Finding Placer Gold and Diamonds in Ontario

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What Is Float?

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Float refers to pieces of mineralized rock that have been separated from bedrock and transported by weathering, erosion, or glaciers.

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Float may appear as:

• Loose boulders in forests or fields

• Rocks exposed in road cuts (e.g Just north of Peterborough where Highway 28 cuts through the drumlin field)

• Pieces found in gravel pits

• Stones lying on eskers or outwash plains

• Cobbles trapped within crevices or fissures

 

These fragments can provide valuable clues about nearby mineral deposits. Boulders that landed on gravel ridges or eskers may remain exposed today, while those that fell into low areas may be buried beneath sediments or muskeg.

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Float Tracing Techniques for Prospectors

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Following Boulder Trains

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One of the oldest prospecting methods is float tracing—following fragments of mineralized rock back to their bedrock source.

Clusters of similar rocks may form a boulder train, a trail of glacially transported material. Think Hansel and Grettle leaving a trail of breadcrumbs from whence they came.

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By studying these trains, prospectors can estimate:

• The width of the mineralized zone

• The direction of glacial transport

• The approximate location of the original source

 

Why are these small Fragments important?

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When mineralized rock occurs not only as large boulders but also as small pebbles and sediment, it suggests the source is somewhere up-ice and if you are fortunate, somewhere nearby. Careful mapping and systematic sampling can help trace the material back toward the source.

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Ice Flow Direction in Ontario

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Did All the Ice Move the Same Way?

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The glacier covering Ontario—the Laurentide Ice Sheet—did not move in a single direction. Instead, it behaved like a dome with several flow lobes. At its maximum extent about 20,000 years ago, the ice sheet was several kilometers thick in places and covered nearly all of Ontario. The main center of this ice mass was located around Hudson Bay, where snow accumulation and cold conditions allowed the ice to grow thickest. From this central dome, the ice flowed outward in all directions across the Canadian Shield and into the Great Lakes region.

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Geologists believe the Laurentide Ice Sheet actually had several major ice domes, rather than a single center. Two of the most important domes influencing Ontario were the Keewatin Dome to the northwest of Hudson Bay and the Labrador Dome to the northeast. Ice flowing from these centers spread southward across Ontario toward the Great Lakes and the northern United States.

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Typical ice flow patterns included:

• Northern Ontario: southwest or south

• Eastern Ontario: south or southeast

• Southern Ontario: flow influenced by Great Lakes basins

 

As glaciers thickened and advanced, the great Lakes basins funneled ice into distinct glacial lobes. Large tongues of ice flowed southward through the lake depressions. Because the basins were lower than the surrounding terrain, ice moved faster and became thicker within them. This focused flow and increased the glacier’s ability to erode the bedrock, which helped deepen and widen the basins even further. 

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Some interesting glacial depositions along the shore of Lake Ontario are the Scarborough bluffs, The Ganaraska Escarpment and the Toronto Islands, which are part of a glacially influenced formation known as a post-glacial sand spit. They were created from sediments deposited by melt water streams flowing from the retreating Laurentide Ice Sheet into what was once Glacial Lake Iroquois, a precursor to modern Lake Ontario.

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The Great Lake basins also influenced the direction of sediment transport across Ontario. As ice moved through the Great Lakes troughs, it carried rocks, minerals, and glacial debris from the Canadian Shield southward into southern Ontario and the northern United States. When the ice began to retreat, melt water flowing along the edges of these lobes deposited large glacial landforms such as moraines, out-wash plains, and eskers around the margins of the lake basins. These deposits still mark the former positions of glacial lobes today.

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Geologists identify these directions from features such as:

• Striations on bedrock (lots to see at the base of the Bruce Peninsula)

• Drumlins (e.g. just north of Peterborough on highway 28)

• Glacial lineations

 

Many regions show multiple ice-flow directions as the glacier expanded and later retreated.

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What Happened When the Glacier Melted

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Retreat of the Ice Sheet

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The glacier did not simply slide backward as it melted. Instead:

• Ice continued to flow forward.

• The front melted faster than new ice arrived.

 

Because of this imbalance, the glacier appeared to retreat northward. The ice retreat was not uniform: different lobes and sectors of the ice sheet melted at different rates, influenced by topography, climate, and the presence of pro-glacial lakes such as Glacial Lake Iroquois and Glacial Lake Agassiz. In southern Ontario, de-glaciation was largely complete by about 12,000 years ago, about 10,000 years from when the ice sheet was at its largest.

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Formation of Glacial Landscapes

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As the ice melted, it created many important geological features for finding placer gold and finding placer diamonds including:

• Moraines

• Eskers

• Out-wash plains

• Large glacial lakes such as Lake Iroquois, the ancestor of modern Lake Ontario.

 

These melt water systems redistributed sediments and helped form the landscapes that prospectors explore today.

 

How do Eskers Form at the Front of Ice Flows?

 

Eskers that form at the front (terminus) of ice sheets develop when melt water rivers flowing inside or beneath a glacier emerge at the glacier’s edge and rapidly deposit the sediment they were carrying. During the final stages of glaciation, large volumes of melt water travel through tunnels within the ice. These sub-glacial rivers carry enormous loads of sand, gravel, and stones that have been eroded from the bedrock beneath the glacier. As long as the water is confined within the ice tunnel, it behaves like a normal river and continues transporting sediment downstream.

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When this sediment-laden water reaches the margin of the glacier, conditions change quickly. The confining ice walls disappear, the slope of the channel decreases, and the flow velocity drops. Because the water suddenly loses energy, it can no longer carry its full load of sediment. Gravel and sand begin to accumulate at the glacier’s edge, forming a ridge that marks the former position of the melt water tunnel. As the glacier retreats backward, the tunnel continues to release sediment along the ice margin, gradually building a long, sinuous ridge.

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These ridges remain on the landscape after the glacier melts away completely. The sediment originally deposited inside the ice tunnel collapses slightly as the supporting ice disappears, leaving behind the characteristic narrow, winding ridge of sand and gravel known as an esker. Because the melt water streams were strong and well confined, the sediments are usually well sorted and layered, with coarse gravels near the center and finer materials toward the edges. When finding placer gold in an esker you will usually find it lower down at the bottom of the gravel layer.

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Eskers formed at the front of ice sheets often connect to other glacial landforms such as out-wash plains or deltas. At the point where the melt water exits the glacier, the sediment may spread outward into a fan-shaped deposit before continuing downstream. These terminal eskers are important to geologists because they mark former ice margins and reveal the direction of melt water drainage during the retreat of the ice sheet at the end of the last Ice Age.

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Why Glacial Geology is Key to finding Placer Gold in Ontario

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Understanding glacial geology is key to finding placer gold in Ontario because glaciers transported minerals in different directions at different times, prospectors must study glacial flow patterns carefully when looking for placer gold and diamonds in Ontario.

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Gold flakes or indicator minerals for gold and diamonds are found in streams, eskers, or gravel deposits; they may point toward hidden mineral sources located up-ice from the discovery site.

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For hobby prospectors exploring Ontario, success often depends less on luck and more on understanding the glacial story that has been written on the land.

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How to Determine the Direction of Ice Flow When Prospecting in Ontario

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Using Float Orientation to Identify Glacial Movement

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Measure the diameter of each float fragment and note whether it has a long axis. If present, record the direction in which this axis points. Plotting these orientations on a map may reveal patterns caused by glacial movement.

 

Glacial ice tends to push, rotate, and transport large rocks as it moves. Because boulders are irregular in shape, the ice exerts the most force along their longest dimension, aligning them parallel to the direction of ice flow. By mapping the orientation of multiple boulders over an area, geologists can determine the dominant flow direction of the glacier, as most boulders will show a consistent alignment – long dimension pointing in the direction of ice movement.

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In addition, pebble trains and elongated glacial erratics can reinforce this information. When combined with other indicators, such as striations (scratches) on bedrock, drumlins, and eskers, the orientation of boulders provides a reliable record of ice movement patterns during the last glaciation. Drumlins tend to be steepest on the side from which the ice was pushing and then they taper down to nothing in the direction the ice was going.

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This technique of studying float markers is especially useful for prospectors tracing gold-bearing float or indicator minerals, because it helps identify the up-ice source of the boulders and associated mineralized material.

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Further evidence of ice movement may include:

• Glacial striations scratched into bedrock
• Fluted ridges of debris
• Drumlins or streamlined hills

 

Topographical maps can also help identify ridges and depressions shaped by glacial flow.

 

Once the direction of ice movement is known, the prospector can search up-ice toward the possible source.

 

Step-by-Step Method for Tracing Mineralized Float in Ontario

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Systematic Float Tracing for Gold and Indicator Minerals

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1. Map the Location
   Plot the float fragments on a detailed map to reveal distribution patterns and the likely transport direction.

2. Study the Shape and Roundness
   Examine how rounded or angular each piece is to estimate how far it has traveled from its source.

3. Determine the Direction of Ice Flow
   Use glacial indicators to establish the ice movement that transported the float.

4. Record Associated Minerals and Rocks
   Note the minerals and rock types in the float to identify potential sources and valuable indicators.

5. Establish Sampling Lines
   Set up stations perpendicular to ice flow to systematically track changes in float abundance.

6. Dig Test Holes
   Excavate small pits at each station to access subsurface sediments for examination.

7. Screen the Material
   Pass excavated material through a half-inch mesh to separate gravel from finer sediment.

8. Sort the Pebbles
   Group fragments by rock type and weigh them to estimate the composition of the deposit.

9. Count and Classify the Fragments
   Record the number and roundness of fragments to help trace the source direction.

10. Test for Magnetic and Conductive Minerals
    Use a magnet or conductivity detector to identify metallic or magnetic minerals in the sample.

11. Process the Finer Material
    Sieve material through a 35-mesh screen and quarter the sample for representative testing.

12. Pan for Heavy Minerals
    Pan each fraction to examine and record visible heavy minerals such as gold, magnetite, or garnet.

13. Save Samples for Further Testing
    Package remaining material for laboratory analysis to detect trace metals not visible in the field.

14. Record Pebble Orientations
    Note the alignment of elongated pebbles to confirm ice movement directions.

15. Move Up-Ice
    If results are promising, continue sampling progressively up-ice to locate the source deposit.

 

By repeating the process, the prospector may gradually trace the float back toward its bedrock source. Remember that despite a few rare exceptions, glacially derived sediment is usually not transported significant distances by the ice sheet, but in an esker the distance can be considerable.

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Why Float Tracing Works for Finding Placer Gold in Ontario

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Glacial deposits in Ontario are often surprisingly local in origin. Many rock fragments traveled only a short distance from their bedrock source before being deposited.

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Because of this, careful float tracing can lead prospectors closer and closer to the original deposit.

Although this method requires patience and systematic work, it has been responsible for the discovery of numerous mineral deposits throughout Canada.

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For hobby prospectors, float tracing offers something equally valuable—the chance to follow geological clues across the landscape and perhaps uncover a hidden mineral source beneath the forests and glacial sediments of Ontario.

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​How Placer Gold Forms in Ontario

 

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Gold is typically found in quartz veins within bedrock, often accompanied by small amounts of other minerals such as pyrite, pyrrhotite, arsenopyrite, galena, sphalerite, and scheelite. Over long periods, weathering breaks down the surrounding rock, releasing gold particles into the environment.

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Because gold is extremely dense, it behaves differently from most other minerals during erosion. When transported by water or glaciers, gold tends to settle in low-lying areas where it can accumulate, such as stream beds, gravel bars, bedrock cracks, and ancient river channels. Over time, these natural traps concentrate gold particles and form placer deposits.

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In Ontario, placer gold is usually found as fine dust, small flakes, or thin scales, with larger nuggets appearing only occasionally. Most nuggets are worn and pitted due to long periods of transport and erosion, reflecting the extensive geological history of the province’s gold-bearing regions.

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Heavy Minerals Associated with Placer Gold in Ontario

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Ontario’s placer gold deposits have some characteristics that make their associated heavy minerals slightly distinctive compared with other regions, largely due to the province’s glacial history and Precambrian geology.

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Common Heavy Minerals Found with Ontario Placer Gold

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Predominance of magnetite, ilmenite, and garnet: While these heavy minerals are common in many placer districts worldwide, in Ontario they are often found in association with finely disseminated sulfide-bearing quartz veins, which were eroded by glaciers and rivers. Garnets in Ontario are often small, rounded, and worn, reflecting long glacial transport. Pyrope garnets, for example, are a notable indicator mineral in parts of northern Ontario.

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Key heavy minerals associated with placer gold include:

1. Magnetite – An iron oxide mineral that is strongly magnetic. It often forms black sand layers along with gold in stream beds and gravel bars.

2. Ilmenite – An iron-titanium oxide that is slightly less dense than magnetite but still concentrates with gold in sediments.

3. Garnet – Specifically pyrope or almandine garnet, which are reddish to violet-red minerals that are dense and resistant to weathering. Their presence can help trace mineralized zones.

4. Chromite – A dense black metallic mineral, often found in glacial gravels with gold.

5. Sphalerite and Galena – Sulfide minerals sometimes found in older placer systems derived from sulfide-rich quartz veins.

6. Other Resistant Heavy Minerals – Such as zircon, cassiterite, and monazite, which are chemically stable and tend to accumulate alongside gold.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In Ontario, many placer gold deposits have been reworked and dispersed by glaciers rather than solely by rivers. In areas further to the south this is less likely. As a result, Ontario’s gravels often contain a mixture of local and up-ice material, producing an unusual combination of heavy minerals in a single sample—magnetite, ilmenite, garnet, and occasionally chromite or zircon.

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This contrasts with typical river-dominated placer systems, such as those in the Yukon or California, where heavy minerals are more directly derived from nearby bedrock and less blended by ice transport.

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In some northern Ontario locations, placer gravels also contain kimberlite indicator minerals, including pyrope garnet, magnesian ilmenite, olivine, and chrome diopside. These minerals can signal the presence of potential diamond-bearing kimberlite sources, which is relatively uncommon in most other placer gold districts.

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Ontario’s placer gold is generally very fine, appearing as “flour gold” or small flakes, and the associated heavy minerals are typically small and worn. This reflects extensive glacial transport and mechanical sorting over thousands of years, in contrast to coarser gold and minerals found in river-dominated placers elsewhere.

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Overall, the Ontario heavy mineral signature—a glacially mixed suite of magnetite, ilmenite, garnet, and sometimes kimberlite indicators with fine particle sizes—provides a subtle but valuable guide for hobby prospectors.

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Heavy Minerals Associated with Placer Gold: Regional Comparison

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Heavy minerals associated with placer gold vary by region, reflecting the local geology and transport processes. In Ontario, glaciers have mixed materials from multiple sources, producing a fine-grained assemblage of magnetite, ilmenite, garnet, and occasionally kimberlite indicator minerals such as pyrope garnet, olivine, and chrome diopside.

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In contrast, California’s Sierra Nevada placers are dominated by magnetite, chromite, garnet, zircon, ilmenite, and tourmaline, with coarser gold reflecting shorter fluvial transport from nearby quartz veins.

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The Yukon’s placer deposits, including the Klondike region, contain magnetite, ilmenite, garnet, cassiterite, and occasional zircon or sapphire fragments, also featuring coarse gold and nuggets derived directly from local metamorphic and igneous rocks.

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These differences highlight how glacial mixing in Ontario produces a uniquely blended heavy mineral suite, while California and Yukon placers reflect more localized sources and coarser material.

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These minerals are concentrated in natural “traps” such as riffles, gravel bars, and ancient river channels, just like gold. Prospectors often focus on layers rich in heavy minerals because they indicate areas where gold may also be present.

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Most commonly it is a sand that accumulateds in your pan, a heavy sand thats composed of finely ground indicator minerals. by its color you can surmise as to what you are seeing. Among the most common sands are those comprised of magnetite and ilmenite—often referred to as “black sand”—garnet, known as “ruby sand,” zircon or “white sand,” and monazite, the so-called “yellow sand.” Tinstone, or cassiterite, is frequently encountered in gold placers and can represent a valuable by-product in its own right. Prospectors should also pay close attention to platinum, which appears gray, and osmiridium, a silvery alloy; both are often more valuable than gold itself. Recognizing and following these heavy mineral sands can greatly enhance the efficiency of placer gold exploration, providing visual clues to the presence of not only gold but other economically significant metals. As you follow up ice (or stream) your indicator minerals should increase in size and end up being something you can identify by its crystal.

 

Why Quartz Is Often Absent from Placer Gold Deposits

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Quartz is often absent from placer gold deposits because of the way placer deposits form and the physical properties of quartz compared with gold and other heavy minerals.

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1. Density and Settling

Gold is extremely dense (about 19.3 g/cm³), whereas quartz is much lighter (around 2.65 g/cm³). During erosion and transport by water or glacial action, the heavy gold particles settle quickly in low spots like stream beds, gravel bars, or cracks in bedrock. Quartz, being lighter, tends to remain suspended in water longer and is carried farther downstream, often leaving the concentrated gold-rich layers largely free of quartz.

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2. Mechanical Sorting

Placer formation is a natural process of mechanical sorting. As rivers and glaciers move sediments, they sort particles by size, shape, and density. Heavy minerals such as gold, magnetite, garnet, and ilmenite tend to accumulate in the same zones, while lighter minerals like quartz, feldspar, and mica are dispersed.

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3. Weathering and Chemical Breakdown

In some cases, the quartz that originally hosted gold in bedrock veins may break down into smaller grains or sand, which are more easily carried away by water. Meanwhile, gold resists chemical weathering, so it remains concentrated in placer deposits while quartz is largely transported out of the system.

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In short, the absence of quartz in placer gold deposits reflects the interplay of density, transport dynamics, and natural sorting processes, which leave the heavy, resistant gold behind while lighter quartz is carried away.

For prospectors, the presence of black sand (magnetite and ilmenite) is often a good sign when panning for gold.

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Eskers: Natural Concentrators of Gold and Heavy Minerals

 

Eskers can stretch for dozens of miles, although they were often formed in shorter segments. Studies show that the sediment within any section of an esker usually comes from a relatively small part of the glacier’s drainage system—often within about five miles of where it was deposited. Because the water flowing through these tunnels moved quickly, eskers frequently concentrated heavy minerals such as gold, magnetite, garnet, and ilmenite, which is why streams that cut through esker gravels can sometimes be good places to pan for gold.

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What are some Gold Bearing Eskers in Ontario?

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While Ontario is not famous for large placer gold deposits, a number of eskers that pass through or down-ice from gold-bearing bedrock belts have long attracted the attention of prospectors. These ridges of well-washed sand and gravel are relatively easy to sample, and in some areas they contain small amounts of placer gold derived from nearby lode deposits.

One of the best known systems is the Abitibi esker network, which runs through the gold-rich Abitibi greenstone belt in northeastern Ontario. Eskers in the Timmins–Matheson–Kirkland Lake region were formed by melt water flowing across terrain that hosts some of Canada’s most productive gold mines. Because glaciers eroded quartz veins and sulfide mineralization from these belts, traces of gold were carried into the glacial sediments. Prospectors occasionally recover fine placer gold in streams cutting through these eskers, especially where the gravel is re-concentrated by modern water flow.

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Another important system is the Munro Esker, a large and well-studied esker near Kirkland Lake and Matheson. This esker extends for many kilometers and is considered one of the more prominent glacial ridges in the region. Because it crosses terrain containing gold deposits of the Kirkland Lake camp, its sediments include material eroded from mineralized volcanic and intrusive rocks. Prospectors have sampled the gravels and nearby creeks for fine gold, although concentrations are usually small and scattered.

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In northwestern Ontario, the Agassiz eskers associated with the former glacial Lake Agassiz basin are also of interest to placer prospectors. These eskers run through areas such as Red Lake and the surrounding greenstone belts, which host some of the richest gold deposits in Canada. Melt water streams that formed the eskers carried eroded material from these gold-bearing rocks, and some gravels contain traces of placer gold. Where modern rivers cut into the eskers, the material can be naturally reworked and slightly enriched, making these spots attractive for small-scale prospecting.

 

Another region with notable eskers is along the north shore of Lake Superior near Wawa and Michipicoten. This area lies within the Michipicoten greenstone belt, which contains historic gold mines and numerous mineral occurrences. Eskers in this district were formed by melt water draining southward toward the Lake Superior basin and contain sediments derived from the surrounding gold-bearing bedrock. While the gold found in these gravels is typically fine and not present in large quantities, the eskers remain interesting exploration targets because they concentrate well-sorted sediments that can preserve traces of placer gold eroded from nearby lode sources.