Figure 2.13. Mount Rushmore, SD. The giant sculptures of U.S. Presidents Washington, Jefferson, Rooselvelt, and Lincoln are carved into the Harney Peak Granite (Paleoproterozoic, 1697 ± 33 Ma), a coarse-grained to pegmatititc muscovite granite containing accessory garnet, biotite, and tourmaline. Visible just below the sculptures is a cross-cutting contact of the the granite with folded metagraywacke layers. Zoom and pan with your mouse or mousepad to look more closely at the contact. Or visit the National Park Service page for more information. John Brady photo.