Greater South Dakota

(includes parts of Wyoming and Minnesota we'd like to claim)


The Needles in the Black Hills


A pinnacle in the Needles



Harney Peak (marked by lookout on the horizon) in the Black Hills, the highest point in South Dakota (7,244 ft.)

Recumbent fold north of Hill City in the Black Hills



Pillow lava structures, rotated to the vertical, in a Paleoproterozoic amphibolite along Castle Creek in the Black Hills



Mammoth tusks in the Mammoth Site, Hot Springs, southern Black Hills


The open pit of the Homestake Mine in Lead in the northern Black Hills



Mt. Rushmore, with the somewhat defaced southeast face



Devils Tower, Wyoming



Columns in Devils Tower, Wyoming



The rock of Devils Tower, porphyritic trachyte to phonolite* with anorthoclase and smaller pyroxene phenocrysts
(*the rock of Devils Tower plots across the trachyte-phonolite boundary on the TAS diagram)



Bear Butte, South Dakota, the eastern-most Tertiary intrusion in the Black Hills



Slim Buttes, NW South Dakota



The Badlands



The Badlands



The "yellow mounds" at the Badlands



The well defined Oakes moraine, northeast of Britton in northewester SD



The northeastern escarpment of the Coteau des Prairies, the upland between the James River and Des Moines
lobes of the Laurentide ice sheet, the most notable topographic feature in eastern SD (not saying much)



The 3.6 Ga Morton Gneiss, Morton, Minnesota