Simi Valley is a synclinal

Syncline

In structural geology, a syncline is a fold, with younger layers closer to the center of the structure. A synclinorium is a large syncline with superimposed smaller folds. Synclines are typically a downward fold, termed a synformal syncline In structural geology, a syncline is a fold, with younger...

 valley

Valley

In geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...

 in Southern California

Southern California

Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...

 in the United States. It is an enclosed or hidden valley surrounded by mountains and hills. It is connected to the San Fernando Valley

San Fernando Valley

The San Fernando Valley is an urbanized valley located in the Los Angeles metropolitan area of southern California, United States, defined by the dramatic mountains of the Transverse Ranges circling it...

 to the east by the Santa Susana Pass

Santa Susana Pass

The Santa Susana Pass is a Southern California mountain pass in the Simi Hills connecting the San Fernando Valley and town of Chatsworth, to the Simi Valley and city of Simi Valley.-Natural history:...

 & 118 freeway, and in the west the narrows of the Arroyo Simi and 118 freeway connect to Moorpark

Moorpark, California

Moorpark is a city in Southern California. It was founded in 1900 by Robert Poindexter, presumably named after the moorpark apricots that grew in the area. The city has experienced a great amount of growth since the late 1970s...

 and Ventura, California

Ventura, California

Ventura is the county seat of Ventura County, California, United States, incorporated in 1866. The population was 106,433 at the 2010 census, up from 100,916 at the 2000 census. Ventura is accessible via U.S...

. The relatively flat bottom of the valley contains soils formed from shales, sandstones and conglomerates eroded from the surrounding hills of the Santa Susana Mountains

Santa Susana Mountains

The Santa Susana Mountains are a transverse range of mountains in southern California, north of the city of Los Angeles, in the United States. The range runs east-west separating the San Fernando Valley and Simi Valley on its south, from Santa Clara River Valley to the north, and Santa Clarita...

 to the north, which separate Simi Valley from the Santa Clara River Valley

Santa Clara River Valley

The Santa Clara River Valley is a valley that runs from east to west through Ventura County and northwest Los Angeles County, California...

, and the Simi Hills

Simi Hills

The Simi Hills are a low rocky mountain range of the Transverse Ranges, located in eastern Ventura County and western Los Angeles County, of southern California, United States.-Geography:...

 to the south. Simi Valley has grown the last few decades, it is rich with history and is one of the largest cities in Ventura County

Ventura County, California

Ventura County is a county in the southern part of the U.S. state of California. It is located on California's Pacific coast. It is often referred to as the Gold Coast, and has a reputation of being one of the safest populated places and one of the most affluent places in the country...

.