The greyish rock on top is the igneous intrusion , consisting of porphyritic granodiorite from the Henry Mountains laccolith .
The pinkish rock on the bottom is the sedimentary country rock , a siltstone .
The greyish rock on top is the igneous intrusion , consisting of porphyritic granodiorite from the Henry Mountains laccolith , and the pinkish rock on the bottom is the sedimentary country rock , a siltstone .