Initiation of a thrust fault, La Verkin Canyon, Utah
Location: on the road to the Toquerville Falls:
Stratum: Virgin Limestone, lower Triassic
As part of the Sevier orogeny much thrust folding occurred in this area. Here we see the initial stage of such a thrust fault. The limestone layer starts to buckle up under the pressure exerted from the left (west). In this case the fold is being pushed under the existing layer at right, and the two layers are separated by a thrust fault ramp, with some attenuated limestone squeezed out as the thrust continues along the ramp. Some of the thrust faults can extend over 100 miles, this is just a baby one, but shows the principle of thrust faulting. Before I saw this fault, I did not realize that thrust faulting also can be pushed under an existing layer, but here its is. The faulting here is caused by ductile deformation with out (much) breaking of the limestone. This type of deformation usually happens at greater depth. Over roughly one half mile, this rock layer showed over seven small thrust faults, some were caused by brittle deformation as a result of earth quakes. Some were underthrusted faults, some were overthrusted.
Initiation of a thrust fault, La Verkin Canyon, Utah
Location: on the road to the Toquerville Falls:
Stratum: Virgin Limestone, lower Triassic
As part of the Sevier orogeny much thrust folding occurred in this area. Here we see the initial stage of such a thrust fault. The limestone layer starts to buckle up under the pressure exerted from the left (west). In this case the fold is being pushed under the existing layer at right, and the two layers are separated by a thrust fault ramp, with some attenuated limestone squeezed out as the thrust continues along the ramp. Some of the thrust faults can extend over 100 miles, this is just a baby one, but shows the principle of thrust faulting. Before I saw this fault, I did not realize that thrust faulting also can be pushed under an existing layer, but here its is. The faulting here is caused by ductile deformation with out (much) breaking of the limestone. This type of deformation usually happens at greater depth. Over roughly one half mile, this rock layer showed over seven small thrust faults, some were caused by brittle deformation as a result of earth quakes. Some were underthrusted faults, some were overthrusted.