Although I’m from a small town named Fresno, I’m from a huge region the San Joaquin Valley. There are so many geologic aspects in the San Joaquin Valley but we must start with history first. The San Joaquin Valley is a sediment-filled depression, called a basin that is bound to the west by the California Coast Ranges and to the east by the Sierra Nevadas. It is classified as a forearc basin, which basically means that it is a basin that formed in front of a mountain range. The Valley dates back more than 65 million years ago to the Mesozoic, when subduction was taking place off the coast of California. However, the plate tectonic configuration of western North America changed during the Tertiary, and the ancient trench that once…show more content… Tectonics refers in part to the forces responsible for moving these plates, but it also refers to the strain that results when plates collide and slide past each other. As such, tectonics represents the driving forces responsible for creating folds and faults, as well the arches and depocenters that characterize the San Joaquin Valley. The San Joaquin Valley and the mountains surrounding the valley are cut by many faults, many of which are associated with recent earthquakes in southern California, the largest one, or course, being the San Andreas Fault. One more of the smaller faults in the San Joaquin valley would be the Garlock fault Movement along these faults has resulted in many, many earthquakes in California over the years. The main earthquakes to hit the San Joaquin Valley in historic times are the Tejon Earthquake in 1857 on the San Andreas Fault and the Bakersfield Earthquake in 1952 on the White Wolf Fault. During the Ice Age The climate of the earth was always changing. When temperatures cooled 40,000 years ago, huge glaciers spread across large areas of North America and Europe. In California, these glaciers covered all but the highest peaks of the Sierra Nevadas. Because less free water was available, many lakes and streams in the adjacent San Joaquin Valley dried up and disappeared. In fact, so much water was locked up in the glaciers, that sea level fell, and the climate became cool and arid. When the Earth warmed 30,000 years later, the glaciers melted. Huge streams formed from the glacial meltwater and rushed down the west slope of the Sierra Nevadas to turn large areas of the San Joaquin Valley into marshes and lakes. Although many of these lakes have since receded, remnants of them remain at Buena Vista Lake and Tulare Lake. Sea level also rose, and the climate became warm and humid once again. Many