The James River Park System - Richmond, VA

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South Geology Tour

Stop 3c: Plutons

DIRECTIONS: Look down at the rocks of the riverbed.

These outcrops are exposures of underground granite masses called PLUTONS. They stretch along the Mid-Atlantic coast and define the boundary between the flat Coastal Plain and the rolling topography of the Piedmont. These formed when hot MAGMA (molten rock) from deep within the Earth’s crust) was injected into the rock above, known as COUNTRY ROCK. As a result of the collision the tectonic plates, North America went down and under (SUBDUCTED) and Africa went up and over. Erosion by the river has exposed this pluton.

see caption below photo

Gull Rock, the last outcropping of Petersburg Granite, at the eastern end of the Fall Zone. (37.523127°N , -77.420572°W).  Looking west, you can see the I95 Bridge and train trestle crossing the James.

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