Home > Contra Costa County, California
Contra Costa County is a suburban county in California's San Francisco Bay Area. As of the 2000 census it had a population of 948,816. The county seat is Martinez.
1 History
1.1 Pre-human
In prehistoric times, particularly the Miocene epoch, portions of the landforms now in the area (then marshy and grassy savanna) were populated a wide range of now extinct mammals, known in modern times by the fossil remains excavated in the southern part of the county. These included pigs the size of modern rhinoceros and rhinoceri the size of modern pigs. In the northern part of the county significant coal deposits were formed in even earlier geologic eras. Other areas of the county have ridges exposing ancient but intact (not fossilized) seashells, imbedded in sandstone layers alternating with limestone. Layers of volcanic ash ejected from geologically recent but now extinct volcanos, compacted and now tilted by compressive forces may be seen at the side of some road excavations. This county is an agglomeration of several distinct geologic terrains, as is most of the greater San Francisco Bay Area, which one of the most geologically complex regions in the world. The great local mountain Mount Diablo has been formed and continues to be elevated by compressive forces resulting from the forces of plate tectonics20th century. Plate tectonics (from the Greek word for "one who constructs", τεκτων tekton ) is a theory of geology developed to explain the phenomenon of continental drift. In the theory of plate tectonics the outermost par and at its upper reaches exposes ancient seabed shale rock scraped from their distant sedimentation location and elevated by these great forces.
1.2 Native American period
There is an extensive but little recorded human pre-columbian history in this area, with the present county containing portions of regions populated by a number of native American tribes. Although the earliest occupation by modern man ( homo sapiens) appears to be about six to ten thousand years before the present period, these numbers are not definitive and may possibly extend to far earlier times, at least as far as non–settling populations are concerned. The known settled populations were were hunter-gatherer societies that had no knowlege of metals and that produced utilitarian crafts for everyday use (especially woven reed baskets) of the highest quality and with graphic embellishments of great æsthetic appeal. Extensive trading from tribe to tribe transfered exotic materials such as obsidianObsidian is a type of naturally occurring glass, produced from volcanoes when the right kind of lava cools rapidly, e. by flowing into a body of water. It consists mainly of SiO (silicon dioxide), 70% or more. Obsidian is mineral-like, but not a true mine (useful for the making of arrowheads) throughout the region from far distant Californian tribes. Unlike the nomadic native American of the Great PlainsThe Great Plains or High Plains are the elevated plains which lie east of the Rocky Mountains in the United States of America and Canada, covering the states of New Mexico, Texas, Oklahoma, Colorado, Kansas, Nebraska, Wyoming, Montana, South Dakota and No it appears that these tribes did not incorporate warfare into their culture but were instead generally cooperative. Within these cultures the concept of individual or collective land ownership was nonexistent. As the culture and its values was not respected by either the first SpanishThe Kingdom of Spain is a country located in the southwest of Europe. It shares the Iberian Peninsula with Portugal, Gibraltar and Andorra. To the northeast, along the Pyrenees mountain range, it borders France and the tiny principality of Andorra. It inc colonizers (who considered the natives both heathans to be converted to Christianity and easily enslavable labor) nor the second U.S.A occupiers (who did their best to exterminate them), little of their history, lore or culture was recorded at the time. Most of what is known culturally comes from preserved contemporaneous and excavated artifacts and from inter-generational knowledge passed down through northerly outlying tribes of the larger region.
