As you travel Missouri Route 30 west of Fenton, Missouri you will pass through many cuts in the landscape that were made to facilitate highway construction. After I moved to the area last spring I noticed a short stretch of bedrock cuts that were different than the rest. Most of the construction cuts expose bedrock that is in nice, horizontal layers; however, about 1.3 miles east of the intersection of Missouri Route 30 and Missouri W/MM at House Springs, something is different.
This is the Eureka–House Springs Anticline. Over a short distance, the layers of bedrock are not horizontal, but are skewed at about a 45° angle.
The Eureka-House Springs structure is the westernmost zone of deformation in the St. Louis quadrangle. The northwest-striking structure is extremely complex. Engel (1939) and McCracken (1966, 1971) described the structure as an anticline that plunges both to the southeast and northwest having a crest near House Springs, MO. Clendenin and others (1993) described it as consisting of three right-stepping en echelon fault segments, each approximately 9.3-15.5 miles in length, and each having a relatively independent tectonic history. They suggest that a minimum of 6.2 miles of left-lateral strike-slip motion has occurred on the structure.
Source: “Bedrock Geologic Map of the St. Louis 30’ X 60’ Quadrangle, Missouri and Illinois” Compiled by Richard W. Harrison
Walk behind the Jersey Wall to the posted coordinates; 38° 25.606 / 90 33.973. At the posted coordinates you will see a small tree near the rock face. A section of the rock face seems to be deteriorating faster than other areas. To log this cache, send me a message describing what is happening to the exposed bedrock and why you think it is happening. Include cache name or GC code in your message. Posts without the requested information will be deleted in a reasonable time unless there are extenuating circumstances.