monzonite porphyry, the most widespread rock unit, is
intruded by biotite granite and porphyritic biotite granite.
Sedimentary and metasedimentary rocks, mainly quartzites and
argillites, have been metamorphosed locally to hornfels and
have been involved in high-angle faulting. Shear zones are
common in the plutonic rocks." Abstract from Arthur Ford's
1962 article in "Science"
on the bedrock geology of the Thiel Mountains.