Introduction (Unit 1) - Eocene Florissant
The uplift of the Rockies had began during the late Cretaceous and by the late Eocene, the region had low to moderate relief. During the late Eocene (36.7 million years ago), volcanic activity increased, beginning with an enormous eruption near present-day Mount Princeton. This eruption blanketed the area with the Wall Mountain Tuff as far away as 150 kilometers (93 miles). Imagine a superheated cloud of ash, rocks, mineral crystals, glass, and debris moving at speeds of up to 100 miles per hour. Two million years later, near the town of Guffey, Colorado a cluster of large stratovolcanoes developed sending ash and lahars into the area. It was this highly active volcanic period that helped to create the ancient Lake Florissant.
Did You Know?
Weevils are a type of beetle, and they are among the smallest complete fossils found in the Florissant fossil beds. The fossil pictured here is less than 3 millimeters long, which is a little larger than the head of a pin but smaller than a pencil eraser. This image is protected by copyright. All rights reserved. To learn More...