Normal faults on the eastern and western flanks of the range separate it from the basins on either side of it. The Ruby Mountains are an example of a metamorphic core complex, and middle and lower crustal rocks have been exhumed to the surface in the footwall of a large detachment fault. A mylonitic shear zone can be traced along the fault on the western margin of the Ruby Mountains, marking the contact between the igneous and metamorphic rocks in the core complex and the undeformed sedimentary rocks around it.