Surface boulders

field of granite boulders
These large, smooth, granitic rocks are found in the valley of the Sauk River, about one-half mile from the quarry where the photograph of a corestone in saprolite was taken. This type of surface is thought to haved formed when softer and more easily eroded saprolite was removed by fast-moving water in what is now an abandoned glacial outwash channel. In effect these rounded surface boulders were at one time corestones, and reflect the irregular distribution of weathering patterns in the saprolite.
Next picture
* Stearns Co. Geology map
* MGS home page
* Minnesota geology