Using the newfound data, the researchers imaged the Sierra Nevada through a technique known as receiver function analysis, which uses seismic waves to map Earth’s internal structure. The scientists found that in the central region of the mountain range, Earth’s crust is currently peeling away, a process scientifically known as lithospheric foundering. Kilb and Schulte-Pelkum reported the findings in December in the journal Geophysical Research Letters.

The hypothesis lined up with previous speculation that the area had undergone lithospheric foundering, which happens when Earth’s outermost layer sinks into the lower layer of the mantle. Now, the study authors believe that the process is ongoing and is currently progressing to the north of the mountain range, according to the study.