Loess
Loess is a unique type of silt, usually containing some clay and in some cases fine sand, which has the propeny of being easily worked, yet being so cohesive that…
Mile 970: Independence Rock
"The great granite loaf of Independence Rock signaled temporary relief from the thirsty barrens, for it stands where the emigrant trail meets the Sweetwater River. Trail tradition held that reaching…
Period Rush
"As a channel evolves into ever more extreme loops, eventually two separate bends may approach one another and join. When this occurs, the river takes the shortcut and establishes a…
Basin and Range
"The termination Farallon Plate subduction probably made the Basin and Range. As North America closed like a sliding trapdoor over the Farallon plate, the plate did not go quietly into the mantle…
Green River Buttes
"Throughout the Green River Basin, many "elevated buttes of singular configuration" rise from the rolling plains, sticking up like flat-topped warts on a sagebrush skin. They stand several hundred feet high, with eroded…
Trail Options West of South Pass
"From South Pass, emigrants had several options for reaching California. They could go to Salt Lake City via the trail to Fort Bridger, and then take either the Salt Lake Cutoff…
Mile 1075: South Pass
"The Sweetwater Valley took the emigrants smoothly uphill 1oo miles to the Continental Divide at South Pass. This fortuitous gap in the Rockies exists because of geologic happenstance. A Wind River-sized mountain…
Mile 937: Avenue of Rocks
"On the high, dry Wyoming plains, the Earth sheds her former grassland modesty and bares her rocky skin, wrinkled by time and mountain upheaval. The beveled edges of bent, tilted strata poke…
Superposition
"The pattern of today's rivers [in Wyoming] only makes sense when we recognize that they inherited their paths from ancestral streams that flowed high above the ridges, in what is now the blue…
Black Hills
"The name (no relation to South Dakota's Black Hills) comes from the dark stands of pine, spruce, and cedar that dot the slopes. Travelers on both the north and south sides of…
Chimney Rock
"Massive in scale, each monument towers hundreds of feet above the floor of the North Platte Valley. Each is made of stacked layers of sandstone, siltstone, mudstone, and volcanic ash. Differential erosion…
Geological Age of the Earth
"In 1665, Irish archbishop James Ussher published a painstaking accounting of the age of the Earth deduced from biblical generations. Ussher's conclusion: God had created the Earth on October 23, 4004 B.C.…