Iowa Geology

Iowa land consists of the deposits left by glaciation. When the glaciers melted they left behind the accumulated debris in them that had been scoured by them in proceeding south. Much of this well-ground-up material was topsoil but there would be also some good-sized rocks. Some of these would have been buried rather deep in the ground, but they would gradually work up closer to the surface, as a result of the land being tilled and cyclic freezing and thawing of the ground.

The first evidence of these buried rocks would be when a plowshare would hit one, perhaps breaking the pointed end of the plowshare. I remember uncle Carl hitting one of these buried rocks with the plow, digging the soil away around it, putting a heavy chain around it and pulling it with the tractor to the pile of rocks in the hog yard. The rocks there had accumulated all during the time the farm had been owned.

Recently (1987-88) one of these large rocks surfaced on the old Joe Johnson farm that we own in Iowa, Vincent’s Jean took a picture of it that I have somewhere.