Geology of Valencia
Valencia rests on many hundreds of feet of alluvium. The hills in the area of Interstate 5 are about 1.5 million years old and are composed of the 1.8 million year old Plio-Pliestocene Saugus Formation. Most of the uplift in these same hills occurred about 1 million years ago during the latter part of the Coast Ranges Orogeny.
Rivers and Drainage
The area is drained by two major creeks. One being the South Fork Santa Clara River to the east and the Santa Clara River to the north. The Santa Clara River begins as a perennial river near Bouquet Junction. There are also numerous small tributaries to the river, mostly coming from the south and east which do add a lot to the river during the rainy season.
Faults and Folds
Many faults run though the Valencia area as the Northridge Earthquake showed back in 1994. Many aftershocks from that quake are still being felt in the Valencia area. In fact, most of the aftershocks were located only a couple of miles west of Valencia. The San Gabriel Fault runs right along Magic Mountain Parkway and through the Valencia Industrial Center. This segment segment of the fault hasn’t been active for a very long time. This does not mean another quake cannot happen though. The Holser Fault near Castaic Junction had a small swarm of quakes just before the 1994 Northridge earthquake. The largest of these quakes was about a 3.5.