Gold Deposits from Continental Glaciation in the American Midwest

This is what a continental glacier looks like

During the past 1 million years there have been three episodes of continental glaciation that has covered the northern hemisphere with vast ice sheets more than two miles thick. Over much of the Midwest these continental glaciers southern boundaries are today marked by the Missouri and Ohio rivers. This is where the glaciers stopped advancing and is an area called a terminal moraine where for centuries all the material the glacier gathered on its way south was deposited in a similar fashion to the pile that forms under a conveyor belt.

The Abitibi:

To the north in Canada lies one of the great gold provinces in the world, the Abitibi, the second-largest gold producing region on earth. As the continental glacier advanced south it scoured the surface of the land in the Abitibi including many lode gold deposits and deposited them at the regions of terminal moraines accounting for the gold found in the northern Midwest of the United States north of the Missouri and Ohio Rivers. Most of the gold will be found just north of the Ohio River with lesser amounts spread across the states from western New York to Missouri.
A gold mine in the Abitibi Gold Belt, Canada

The glacier explains the presence of gold in the northern United States, and the absence of placer gold in Ontario. In its travel south from the Arctic it passed over an area of sedimentary rocks south of Hudson and James Bay with no gold leaving the soil covering the Abitibi region with no gold hence the absence of placer deposits.

Gold in the Midwest:
A terminal moraine in the foreground where the glacier stopped and just dumped its load.

A terminal moraine is characterized by a hummocky appearance of many small hills and valleys and large deposits of sand and gravel. Subsequent reworking of the material by streams in a terminal moraine has resulted in the concentration of gold in the channels of streams throughout the area. Most of the gold is concentrated in an area north of the Ohio River, and just to its north, however enough gold was dragged down from Canada that it can also be found in the sands along the Great Lakes and in thin deposits across the states.  .