Post Rock Country

Last blog with a connection to Mr. Obama.  Driving on I-70 across the western part of Kansas you cannot help but notice a sign welcoming you to Post Rock Country.  After wondering if you have entered some strange enclave of Celine Dion partisans, you will start noticing that fence posts along the interstate are made from stone and not from wood.  Turns out that in a land of few trees and many cattle, the best way to build a fence was to use the local limestone, a yellow-tan rock easily quarried from just below the surface.  The layer, known locally as Fencepost limestone, comes out of the ground soft and easily worked, but hardens soon after exposure. 

Post Rock Stone Fenceposts (From Kansas Geological Survey)

“Had it not been for stone fence posts, prosperity might have been a long time coming to much of north-central Kansas,” wrote Grace Muilenburg and Ada Swineford, in Land of the Post Rock: Its Origins, History, and People.  The authors report that stone fence posts can be found in an area that covers about 200 square miles, from Hays to Salina and then extending northeast to the Nebraska border and southwest toward Dodge City.  No one knows when the first post appeared but most references point to the early 1870s, as immigrants began to move into the state.

Homesteaders put up hundreds of thousands of the posts, each of which weighed between 250 and 450 pounds.  A 160-acre-property required 360 posts and 40,000 feet of wire.  (In the 1880s barbed wire started to become popular, which helped make wire-and-post fencing much more feasible and cheaper.)  To cut the stone posts, which were generally eight to twelve inches thick—depending upon the layer quarried—masons used a plug and feather technique. 

First step was to drill a row of holes about six to eight inches apart.  Next, the masson dropped into each hole two metal, half-round shims, each bent at the top to prevent them from slipping into the hole.  Between the shims, known as feathers, he placed a metal wedge, the plug.  To separate the rock, he pounded the plugs in succession until the rock split.

Plug and feather stone splitting (Photo from Kansas Geological Survey)

Fencepost limestone forms the top layer of the Greenhorn Limestone, a rock unit deposited 95 million years ago.  During this time, a sea ran up the middle of North America.  The Greenhorn includes chalky, fossil-rich, and more limey layers.  Fossils include ammonites, clams, and petrified wood, some of which appear in the fence posts. 

The post rock era ended in the 1920s, as farmers and ranchers began to use wood and steel, transported by railroads and cars.  Over the following decades,  the posts’ popularity lead to periodical revivals and one can still find many of the beautiful and unusual posts, a testimony in stone to the ingenuity of plains dwellers.

A good gigapan photo of the fenceposts has been posted by Ron Schott. 

 

 

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