It frustrates me that I cannot seem to find much about the geology of my own county, but I keep looking. Lately I've discovered that most of the rocks are from the early proterozoic, which was when the gathering up of oxygen in the earth's atmosphere took place. It was a time of major glaciation. Life consisted of complex single cell organisms, and some multi-celled. Other rocks are from the late archaen, which preceded the proterozoic. The atmosphere lacked free oxygen. Liquid water was present. Temperatures were close to modern day temps. Stromatolites were present.