There's a topographic mystery in the eastern Ozarks' St. Francois Mts: why are so many summits underlain by old Precambrian igneous rocks while the valleys are underlain by far younger sedimentary rocks? In this chapter of our Geology of the Ozarks series, we visit many different sites to explore possible explanations, demonstrating evidence that there's an ancient mountain range buried beneath this part of the modern Ozarks, its summits poking through a mantle of younger deposits.

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Chapters:
00:00 Intro
01:38 Elephant Rocks
02:48 Johnson's Shut-ins
03:41 Highway 72 roadcut
05:49 Taum Sauk hydroelectric plant
08:15 Taum Sauk Mountain
09:09 Regional 3D models & cross-section
10:39 Revisiting faulting
12:37 Effects on modern terrain
13:57 Summary & outro

Resources cited in the video:
- Kisvarsanyi et al., 1981, Guidebook to the Geology and Ore Deposits of the St. Francois Mountains, Missouri: https://share.mo.gov/nr/mgs/MGSData/B...
-Seeger & Palmer, 1998, Synsedimentary Tectonism in the St. Francois Mountains Region, Southeast Missouri (Association of Missouri Geologists field guide): http://www.missourigeologists.org/Ear...