I am in a deep rut.  More precisely, I am standing in wagon ruts almost 5 feet deep near Guernsey, Wyoming.  These impressive tracks were worn into soft rock by the wheels of thousands of emigrant covered wagons across this continent in the mid 19th century on their way to California, Oregon and Utah.

When it was possible, the trails followed the low and steady grade of the Platte River.  So why did they climbed the hill and cause those ruts?

Just upstream from the ruts, the Platte River cuts through the Hartville Uplift, which is composed of much harder rocks.  In doing so, the river created a narrow canyon with steep walls.  It is beautiful, but there is no room for a wagon road.  The emigrants had to detour over the lesser obstacles on the south, thus creating the famous wagon ruts.

There are many other places in Wyoming, such as Bessemer Bend or South Pass, where geologic features dictated the transportation routes.  Topography still affects highway routes.  For example, Interstate 80 uses a sloping geologic feature known as the “gang plank” to get through the Laramie Range and avoids the snowy Range.

The relationship between geology and human activity is one of the enduring wonders of Wyoming.  I am Gene Gade of the University of Wyoming, cooperative extension service.