Terry Steinborn -- one of our members is teaching a OLLI class on volcanos . One of the class questions was how deep is the bottom of the crust? There is a good map of how deep in the following article:
Mohorovicic Discontinuity - The Moho - GEOLOGY.COM
Take a look at where we are --in our part of the basin and range -- it is thick in our portion of the crust.