Glacial geology
Look at this map, of a small part of the state of Minnesota:
See the wide channel that runs from left to right with the windy river in it? You are looking at one of the most amazing stories in geological history ever. I'd like to tell you about it.
When not in flood, the meandering river is little more than a slow moving stream in a wide marsh, with thickets and stands of pioneer trees dispersed among reeds and pools of open water. Largely bypassed by farm, rural and urban development, it is in this channel that the state's rare cougars live, and where some of the best birding in the…