Thursday, December 9, 2021


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Publication 36. Geological Series 30.CLAYS AND SHALES OF MICHIGANANDTHEIR USES (1924)

The areas that are richest in clay are the areas circled in red. They used to be lake bottoms. Soil that is eroded goes SOMEWHERE. The rocks and gravel stay in the river beds or esker/moraine. Sand is deposited close to shore. Only the silt and clay particles are carried out, away from the mouth of the rivers and streams.

Outside of those circled areas, most of Michigan is dominated by sandy-loam and sand.

Unfortunately, Eaton County is eighty miles from the closest clay-rich area, Ypsilanti, Michigan.

But all is not lost. Smaller pockets of clay can still be found. The same mechanisms apply but on a much smaller scale.

Kettlehole lakes are a feature of glaciated landscape. The red arrows show where sediment was eroded. The finest material will be under the "peat" in the center of the kettlehole.

Clay deposits can also be found in alluvial fans. You might think it odd that the shaded area indicating the alluvial fan is on the other side of the river that the tributary is feeding. Remember that river channels meander.

Perched water-tables

Have you ever been walking across some "upland" field, perhaps climbing a gentle grade hunting pats, quail or pheasant. Suddenly, your footsteps were making the unmistakable "Squelch-suck" sounds of walking over mud.

Or perhaps you saw a patch of cattails or rushes or phragmites on that slope...a place where they had no business being.

If you have, then you ran across evidence of a perched water-table. Imagine a sponge sitting on top of kitchen table. You pour water on the sponge. It flows downward until it hits the table and then it flows sideways.

Those unexpected wet-spots are where the interface of an underlying clay shelf with porous overburden is exposed.

Key Point: Clay shelf = minable clay deposit.


  1. Dig just below the top soil in my neck of the woods and all you'll find is clay and rocks.

    1. I think that if I were seriously looking for clay I would talk to the local guy who digs foundations and drainfields and the well-diggers. I could also talk to the farmers and ask where the tractors bog-down pulling the plows.

      I am not trying to make enough bricks to build a city but to make enough fire-bricks to start a local woodstove industry in this new Weimar Republic. I don't need 200 acres of clay deposits.

  2. All that clay. Don't know what to make of it.

  3. I'm in the Clay Pan area of Southern Illinois. North, there are deep prairie soils, and South there is deep loess overlaying the hills. Grass, other than fescue was not a problem in tree planting projects because the grasses cannot root any deeper than the trees we planted. This made planting projects a bit simpler for me because I didn't have to use herbicides, other than killing fescue before planting. Those seeps are special. Don't even try to machine plant in them. The uninitiated will bury a tractor to the frame when pulling a tree planter. One of my absentee landowners borrowed a tractor and buried it twice in one day. If you find a soft spot, don't go over it again, because it will have liquefied with the first pass. Each lug on a tractor tire will move about an inch of soil. One revolution will bury you. I can be very discouraging when talking to new landowners.

  4. I well remember my absolute puzzlement when I first encountered muskeg on a mountain side. Everything was all flowing down the mountain - and yet there I was in the middle of muskeg.

  5. Your map includes Saginaw valley in the clay zones. I'm here in midland and its very sandy. My wife has lived here, Sanford, Bridgeport and Saginaw and she says they have all been sandy.


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