General Facts
Agua Dulce is located in the Sierra Pelona Valley, between Santa Clarita and Acton. The valley floor is mostly composed of an early Quaternary alluvium. It is one of the last remnants of a depositional surface which covered much of this region. The valley floor here is currently being eroded by the tributaries of Agua Dulce Creek, which flows to the south to the Santa Clara River. Many houses along Agua Dulce Canyon Road are built on top of this well-drained surface. This type of erosion is called headward erosion. In time, Mint Canyon Creek may breach the low divide near Sierra Highway and Agua Dulce Canyon and capture some of the runoff from the Sierra Pelona Mountains. This may take many thousands of years to do so though.
The rock underlying this valley floor is mostly Oligocene Vasquez Formation, about 24 mya. Vasquez Rocks are also composed of the Vasquez Formation and the shape is due to differential erosion of parts of the formation. It is primarly composed of alternating layers of sandstone and conglomerate, with the basal portion of the formation being basalts, a volcanic rock. The Sierra Pelona Mountains to the north are made of Precambrian Pelona Schist and are a part of the Transverse Ranges.
In nearby Tick Canyon, a borax mine flourished from 1906 to about 1920. The remains can still be seen along Davenport Road about half way between Sierra Highway and Agua Dulce Canyon Road. Many minerals can be found there including howlite, colemanite, ulexite, and many others. The minerals were from the Vasquez Formation.
Rivers and Drainage
Most streams in this area drain southerly into the Santa Clara River via Agua Dulce Canyon. These streams are eroding headward into the Sierra Pelona Valley floor creating a terraced appearance. There is a smaller drainage divide to the northwest that separates the Mint Canyon drainage from Agua Dulce Canyon. Mint Canyon, heading westerly, also drains into the Santa Clara River near Solemint in Santa Clarita.
Faults and Folds
The Elkhorn Fault, one of the faults in the area, trends in a generally east-west line near Escondido Canyon Road. The signs of folding are shown in road cuts and at Vasquez Rocks. They are steeply dipping away from the axis of a large anticline. This faulting is also partly responsible for the marshy area near Agua Dulce Canyon Road and Escondido Canyon Road. This is caused by the fault line itself acting as a dam of sorts underground, both limiting groundwater movement and bringing it closer to the surface.
