Edward Cox

Field/Lab Assignment Part 1

My first sample that I have identified was Shale. I found this sample in Lake Millerton, just outside of Fresno county and Friant. This sample is a sedimentary rock, which in this location there are a lot of sedimentary rocks. This was found were the water level usually is when the water is up after our snow melt. Water is pretty low right now. This sample is was found were 2 different streams come into the main lake. This location was in a valley that was really steep.

My Second sample that I have taken is Oncolites (algal limestone balls) that float in a carbonate-mud matrix in the Cambrian-age Chambless Formation. This limestone formation crops out in many areas throughout the Mojave national Preserve region. These spheroidal oncolites formed by algae and or cyanobacterial growth in shallow warm marine waters of a carbonate platform environment. This sample was taken in the Mojave Desert in California

The Third sample that I took was the Mitchell Caverns in the Providence Mountains State Recreation Area. This area has been developed for commercial visitation. This cavern formed in Limestone of late Paleozoic age (Pennsylvanian age and Permian age Bird Springs Formation). The cavern formed a long, long time ago when the bedrock was constantly exposed to groundwater, allowing dissolution of the limestone to occur. Today, the cavern is high and dry, and it is more that 500 meters above the valley floor and a constant supply of groundwater. This sample was also taken in the Mojave Dessert.

My forth sample is also in the Mojave Dessert. This is fractured granite bedrock that is exposed along Globle Wash in the Providence Mountains.

My fifth sample is of Lava rock. A lava tube forms where the surface of a lava flow cools, but lava continues to flow below the surface. This example in the Cinder Cones and Lava Beds area, the surface layers of basalt lava have collapsed, creating an entrance to the lava tube. More cinder cones are in the distance.