Geology

Around 10 million years ago, when the shallow ocean that covered this area was receding, the continents were moving and sliding along faults. The movement of the earth and the pressure associated with it, pushed the mountains up and pulled the valleys down. Volcanos developed and erupted as a way for the earth to release its stress. Three to five million years ago, Sonoma Mountain, the long mountain you are facing to the east, was a volcano and the valley in which you stand was approximately 1,000 feet deeper than it is now. Where did the volcano go? Much of the volcanic debris has been eroded off the hillsides into the deep canyon below you. Over 1,000 feet of fill! Creeks like Adobe Creek have have carried and continue to carry eroded material down from the mountains into the valley. As you walk to Station 3, keep our eyes on the freshwater ditch to your right for a western pond turtle. They occasionally can be seen sunning themselves on clumps of vegetation, logs, rocks or on the shore.

Tour text from "Self Guided Tour of Shollenberger Park" available on site.