ABSTRACT OF IGNEOUS ROCK HISTORY

Oklahoma has several different types of igneous rock that has formed in many ways with different minerals to shape the state we know today. This is a report over the formation and alteration of igneous rock in Oklahoma, specifically in the Wichitas. The oldest rocks we have dated in Oklahoma are the Precambrian igneous and metamorphic rocks that formed around 1.4 billion years ago. Igneous rocks are formed by magma, if it is below the crust, or lava, which is above the crust. This can be determined by looking at the crystals of the rock, crystals present to the unaided eye represents a slower cooling process, indicating formation from magma. A lack of crystals visible to the naked eye means that the rock had a faster cooling process, illustrating that the formation was originally lava.

The approach our team took for determining the formation and alteration of the rock was taking a field day to view the outcrops of the Wichitas to just familiarize ourselves with the type of rock and to view the erosion patterns. The area of the Wichitas had mountains that ranged in elevation as well as the valleys having a gradual slope upwards. We also took a field day to see the ten-acre rock in Tishomingo to view the erosion patterns as well as the area. This formation was rounded at the top and most of the surface was smooth and the area surrounding it was rather flat. At the Wichita sites we saw water erosion patterns, chemical weathering, and also mass wasting. At Tishomingo the majority of the weathering was water erosion. We also viewed thin sections of the Wichita igneous rock at Rose State lab and determined composition to better understand weathering patterns.

The weathering patterns we saw at the Wichita sites was indicative of actually covering up the base of most of the elevated surfaces, like the mountain range. The water weathering we viewed were catalysts to many deeper trenches in the area due to the transportation of soil and rock to a different area, carried by water. The chemical weathering we viewed also altered the rock formations because it dissolves, loosens, or decomposes rock into residual material, like sediment. These weathering processes alter the rock formations and impact surrounding areas.