|Red rocks of the Queenston Formation|
What happens as soon as you lift up a mountain range? It starts to erode. The stuff eroded off this mountain range was carried by large river systems to the west, especially into what is now eastern Ontario and western New York and Pennsylvania. The sediments were dumped into the shallow sea that was there, forming a huge delta, probably quite a bit larger in area than today’s Mississippi Delta. The pile of sediment is called a clastic wedge, because it contains clastics – broken pieces of rock, worn down to gravel, sand, silt and mud, and it’s a wedge because it’s shaped like a doorstop – thickest toward the mountains, and thinning off to the far west. It’s called the Queenston Delta and the rocks in it are called the Queenston Formation.
|Yellow=sandy sediments of Queenston Delta.|
Mud across Ohio is part of the system, too.,
The Queenston Delta system was so vast, and contained so much sediment, that it may have contributed to a reduction in atmospheric CO2 which could have reacted with all that exposed sediment. Maybe even enough to reduce the ongoing Ordovician greenhouse situation and to contribute to the glaciation that’s coming at the end of the period.
—Richard I. Gibson
Photo by Ian Muttoo licensed under the terms of the cc-by-sa-2.0
Map from Ohio Geological Survey, Ohio Geology, Fall 1997 (PDF)