Week 9: Geologic Time

I live in Pleasant Grove, which has seen many changes since the Paleozoic Era hundreds of millions of years ago.

In Paleozoic times, Pleasant Grove was under the water of the Paleo-Ocean. It was close to the shore, and covered by shallow water. The sediment deposited there was most likely well-washed quartz sand.    

In the Early Jurassic period, Pleasant Grove was cut off by the moisture of the ocean by the mountains that were rising in the west. Desert sands blew into Utah from the north and northwest. These sands formed dunes that eventually formed sandstone.    

During the Late Jurassic period, dinosaurs roamed the earth near Pleasant Grove. Utah was a swampy lowland. Volcanoes began forming mountains nearby.    

During the Late Cretaceous period, Pleasant Grove was located near one of many rivers flowing towards the Inland Sea. Dinosaurs continued to roam. The Pacific Plate collided with the continent and produced high mountains.    

During the Paleocene era, the high mountains around Pleasant Grove eroded. Sediments filled the inland sea and the rivers that flowed into it. The pressure from the Pacific Plate pushed the land nearby up into a plateau.    

During the Eocene Era, the mountains around Pleasant Grove eroded to almost nothing. The ground itself continued to rise in elevation from the pressure of the Pacific Plate. Organic matter produced fossils and oil shales. 

In the Oligocene Era, Pleasant Grove continued to rise, while rivers started carving through the elevated plateau. Plains and mountains surrounded the area. As extension began, volcanic activity started to occur.    

In the Miocene Era, Pleasant Grove continued to rise and tilt northeastward. It was covered by a lake, formed by the extension as two plates pulled apart. Volcanic activity continued nearby.    

During the Pleistocene Era, Pleasant Grove was completely covered by Lake Bonneville. The climate was colder and glacial activity took place. Battlecreek and Grove Creek Canyons were carved out by rivers.    

Presently, Pleasant Grove is at the foot of the Wasatch Mountains. These mountains were formed by plates pushing together and by glaciers. Also near Pleasant Grove is Utah Lake, one of the last remaining parts of the great Lake Bonneville. 

Pleasant Grove has seen an incredible amount of geologic activity since the Paleozoic Era. From being the shore of the western ocean, to desert, to swamp, to volcanic activity, to plateau, to the bottom of a great freshwater lake, and finally to the base of a great mountain range. This assignment has made me wonder: Is there a better place in all the world than to study geology than Utah? What a wonderful, diverse geologic state we live in.