I admit, the initial going over of the Wisconsin series of glaciations was a ltitle bit rocky. Once past that, the influences on our soil, our plant communities, our ecosystems all follows from that initial action, glaciations of over 10,000 years and more.
The emphasis here is on the plant communities dependant on their surrounding soil type, degree of exposure to the sun, even microniches such as the soil and plants found at High Cliff, with it's dolomite base. All due to glacial actions, and subsequent soil types.
Many call this the Bible of modern ecology. It charts, graphs, and explains, any area left wild that you can find. It also does so for the civilized areas, increasing in number, and sadly, influencing the natural course of events. Other midwestern states look to this work, as their description of their lands.