Why are landslides and rapid erosion common in parts of the Coast Ranges?

Landslides and rapid erosion are common in parts of the Coast Ranges primarily due to their complex geological composition and tectonic activity.12

The ranges are characterized by folded and faulted sedimentary rocks, such as gray mudstones and siltstones, which are inherently susceptible to weathering and instability. Furthermore, the region is situated along the leading edge of lithospheric plates, where ongoing tectonic processes—including movement along major fault systems like the San Andreas Fault—contribute to the rugged, high-relief topography. This steep terrain, combined with the presence of less-resistant sedimentary materials, makes the landscape particularly prone to mass wasting events like landslides.1342

Additionally, the region experiences significant variability in precipitation, which acts as a primary driver for the erosion of these geological features.2