Dry Creek Petrified Tree Forest
I-90 east from Buffalo to the Red Hills

The Dry Creek Petrified Tree Environmental Education Area (EEA), set aside as such in 1978, is located about 9 miles east of Buffalo, Wyoming. A parking area, picnic table, and interpretive facilities can be found here.

As you travel around a loop nature trail about 0.8 mile long, you will go back 60 million years to the geologic era of the Early Eocene when this area was shaded woodlands and mossy glades. You will learn how the uplifting of the Big Horn Mountains helped to create the prairie ecosystem we see today. And you will also learn about early vegetation and the formation of coal, scoria, petrified trees and other indicators of the past.

This area was very different from what can be seen today. Giant trees grew in a jungle-like area somewhat like the Okefenokee Swamp in southern Georgia. A large system of rivers flowed north to a distant ocean. Huge swamps filled the wide, flat plain between the Big Horn Mountains and the Black Hills. There may have been turtles, crocodile-like creatures, large fished similar to modern gars, and primitive mammals and birds.

Scoria is a sort of natural brick formed from shale or sandstone that has been “fired” when coal seams caught fire and burned back into the ground. Scoria can be crushed and used as a rock aggregate for road pavement, hence some of the red color roads in the area, and as a road base for unimproved roads. The red color is produced by iron oxides in the rock. Scoria can be crushed and used as a rock aggregate for road pavement; hence, some of the red-colored roads in the area, and as a road base for unimproved roads.

Coal forms slowly over great periods of time. The coal beds in the area originally accumulated as peat deposits that formed from the leaves, branches, stems, and roots of trees and other plants that grew in the swamps. The peat beds probably were buried when a nearby river flooded, covering the area with sand and mud. After millions of years under thousands of feet of sediment, the peat gradually changed to coal. (One coal seam near Buffalo, the Healey, is about 200 feet thick in places.)

As erosion and uplifting began to change the earth’s surface, many coal seams were exposed to air and caught fire. As the coal seams burned back into the hillsides, the intense heat changes the normally soft brown and gray rocks to a hard red material—scoria. At station 2 you will learn about plants that helped to form the coal.

The ecosystem of the swampy plain played a significant part in the development of coal, an important energy resource today.

Article courtesy of Bureau of Land Management.