On October 12, I took a day trip to a few of Minnesota's Scientific and Natural Areas (SNA) in the western part of the state. Western Minnesota is prairie land, and topographically speaking, quite boring. We in the Midwest U.S. can get excited at the smallest things, as mountains, picturesque lakes or oceans, etc. are just not outside our back doors.
First stop: Gneiss Outcrops SNA (241 acres).
Along the Minnesota river (which was gigantic in ancient times), rock out crops are many due to the removal of earth by what was then the Glacial River Warren.
Lichens seem to love this rock, and it was difficult to find any amount that was not covered with them. The following might paint me as a geologist, but really, I am (hopefully correctly) interpreting from the posted information at the site.
1. Granite gneiss.
2. Garnet-biotite gneiss. (Or might it be an igneous rock complex?) At any rate, the rocks are quite interesting here.