Thanks to Kim and Ron for pointing out that Herbert Hoover did in fact, have a degree in geology, though his professional career was primarily as a mining engineer. Hoover was part of the inaugural class at Stanford and graduated in geology in 1895. He began his career working for the USGS.
So, here is part II of geologists who have been prominent in politics:
Herbert Hoover [left], President of the U.S. from 1929-1933. According to wikipedia, his lectures at Columbia and Stanford universities were published as Principles of Mining in 1909, which became a standard textbook. Hoover and his wife also published their English translation of the Renaissance mining classic De re metallica in 1912; their translation is the most important scholarly version of the work. It is still in print.
Harrison "Jack" Schmitt [center] is the only geologist to have walked on the moon. He has degrees in geology from CalTech (BS) and Harvard (PhD). After his career as an astronaut, he served as U.S. Senator from New Mexico, 1977-1983. [some bragging rights - I've gotten to know Jack from serving with him on the AAPG Astrogeology Committee]
Emil Constantinescu [right] served as the second president of post-Communist Romania from 1996-2000. He was a professor of geology at the University of Bucharest and elected president of the university in 1992. He currently serves as head of the geology faculty at the university.