©     UNCONFORMITYS

     
    


    At Sicor point Scotland in the year 1788 James Hutton the father of modern geology found something special. That something special changed his view about time and the geological processes. While looking for rock formations along the east coast of Scotland he found his famous unconformity. An angular unconformity. He knew then that geological processes like deposition of sediments, uplift of mountains and erosion took millions of years not hundreds of thousand of years like the church had said. In his minds eye the rock formations spoke to him and he could read a great story in them of how the sediment was laid down in a great ocean. Of how the sediment was buried and compressed and how the sediment became solid rock. How the rock formations were then up lifted and turned on edge by great tectonic forces. Then later eroded down leaving an eroded surface. Then covered over by more sediment which after many more millions of years turned to hard rock and was then up lifted to be eroded down again. This unconformity was named Hutton’s unconformity in honor of the great geologist who led the way for other geologists to follow. Because for its day this was as great of discovery for the science of geology as the theory of plate tectonics is today. His discoveries about the young science of geology and of other earth sciences play a pivotal role in how the earth’s secrets were then and now reveled to scientist.

Today three unconformities are now recognized. They are angular unconformities, nonconformities and disconformities.

An angular unconformities is said to exist when the sedimentary rock formations have been tilted on there sides and an erosinal surface has formed along the edge of the formations and is said to be truncated. A horizontal layer of sediment is then laid down upon the erosinal surface. The erosinal surface represents lost time in the depositional record and is the angular unconformity not the rock around it. An angular unconformity can represent million to billions of years that are missing in the rock record.




Sedimentary rock formations are some times deposited parallel to one another with an erosinal surface between them and no disturbance of the rock exists but the erosinal surface. This is a disconformity and also represents lost time in the deposinal record.




Sometimes sedimentary rock is deposited over extrusive igneous rock or metamorphic rock after the extrusive igneous rock or metamorphic has been eroded down forming an erosinal surface this is called nonconformity



On a rock column diagrams the unconformity is depicted by a red wavy line.

Lots of unconformity’s are found in Utah here are a few examples shown below

ANGULAR UNCONFORMITY SALINA CANYON UTAH


ANGULAR UNCONFORMITY ECHO CANYON UTAH


ANGULAR UNCONFORMITY WENDOVER UTAH



NONCONFORMITY WILLARD UTAH

the line just below the lighter rock is the nonconformity