Slate geology
The Slate Valley of Vermont is unique in the world because of its formational history.
Metamorphism of shale into slate and the different cooling temperatures acted to make many different colors of slate in this very small area. It is world renowned for this fact.
The slate in this region has been formed between 450 and 650 million years ago during the Cambrian and Ordovician Periods of the Paleozoic Era.
The reason why slate is so widely dispersed throughout the world is due to plate tectonics. At one time, every continent on the earth was combined into one major landmass, Gondwanaland.
The relevant fact is the incredible similitude between the purple slate of Vermont and the purple slate of Wales !
There are 5.000 km between the 2 quarries but they’re similar :
Vermont purple slate
VS
Welsh purple slate
Because the continents were all joined together, there were shared areas of similar rock formation.
For example, the slate in Vermont and New York has similar formation times and characteristics to the slate from Wales.
Nowaday, the slate valley is a fairly large área that covers parts of two different states. It is located in Rutland County, Vermont and Washington County, New York.
Overall, it measures approximately thirty miles from north to south and about ten miles from east to west, a total area of about 300 square miles.
