Murrieta Hogbacks

The Murrieta Hogbacks are Miocene basalt capped granitic hogbacks located in northeastern Murrieta on the southern end of the Temescal Mountains of Riverside [County, California].

Geology

The Murrieta Hogbacks are underlain by Cretaceous granitic rocks of the Peninsular Ranges Batholith. On the north half of the hogbacks, by foliated biotite-hornblende tonalite and on the southern half by hornblende gabbro. The basalt is potassium-argon dated to 10.4 to 10.8 million years and is a remnant of a channel-filling basalt flow, overlying a thin deposit of unconsolidated gray stream gravel, indicating that the basalt had filled in a former water course.