Welcome to the Geological History of the Sacramento State Campus

Summary

The organisms that are currently found on the Sacramento State campus and the surrounding area are the consequences of the interplay of large-scale geologcal and biological phenomena.  This page is an overview of the geological processes that have shaped this area.

Introduction

The driving force of much large-scale geology is known as "Continental Drift". It refers to the theory, more properly referred to as "plate tectonics", supported by massive amounts of data and testing, that the surface of the Earth is not static, but rather consists of a collection of "plates" thet essentially float around on the underlying mantle. These plates move relatively slowly, on the order of a few centimeters (parts of an inch) per year, but over long spans of time, this has dramatic consequences.

The bulk of California sits on the North American Plate, but not all. The westernmost portion of the state lies on the Pacific Plate. The boundary between these two is called the San Andreas Fault and runs north-south through the East Bay, including right through Berkeley and is most visible as Tomales Bay.  As these giant plates move slowly past each other, they exert tremendous pressures, responsible for much of the large-scale geology of California, as well as dramatic events like earthquakes and volcanoes. 

For a detailed discussion of the geology of the northern Sierra Nevada, the University of California Museum of Paleontology offers an excellent overview.

The net result of these large scale events is that the current city of Sacramento sits at the confluence of two mighty river systems.  The Sacramento River, originates in the Klamath Mountains at the far north of California and flows generally southward to just past present-day Sacramento, where it then joins the San Joaquin River, to form the Sacramento-San Joaquin Delta region, which then flows out to the Pacific Ocean, via San Francisco Bay.   In the city of Sacramento, the Sacramento River is joined by the American River. The American River flows west down from the Sierra Nevada to the confluence with the Sacramento River.