The forests, wetlands, and farms that we see in the Prosper Valley today are all ultimately tied to the bedrock beneath them, formed from events that occurred millions of years ago. Walking around the Valley, rocks with shiny flecks in them, or others that seem worn and ‘holey’ may catch your eye. These rocks are part of a large swath of bedrock described as the Waits River formation, which runs the length of Vermont from Canada to Massachusetts. Geologists believe that this band of rock once marked the ancient shoreline of the Iapetus Ocean, a sea that predated the Atlantic Ocean and spanned the equator over 500 million years ago!
This Waits River Formation is defined as an “impure limestone or marble weathering to a brown punky crust… with mica schists”. The term ‘formation’ refers to the fact that it is a mix of rocks from two different origins. Materials deposited in the Iapetus Ocean on the shallow continental shelf mixed with materials from plant and animal life, and were eventually metamorphosed. These became mineral rich limestones. The calcite in these limestones dissolve easily, leaving many of the rocks of the Valley with a pocked, worn look. Finer mud materials from the erosion of the mountains settled out further in the Iapetus ocean and became schists. These rocks are easily identifiable in the Valley because the shiny mica flecks within them catch the sun.
Bedrock geology map of the Prosper Valley
Bedrock in the Prosper Valley, Vermont
A rock outcrop in the woods in the Prosper Valley, Vermont
Road cut through the bedrock in Barnard, Vermont