The James River Park System - Richmond, VA

6 of 10 • start over

North Geology Tour

Stop 6: Get Cracking

DIRECTIONS: Walk about 46 m (50 yd) upstream from Hollywood Rapids on either the rocks or the path. Look for CRACKS and STRESS LINES, thin lines in the granite that are straight and long. (37.52959° N, 077.45529° W)

How did the granite crack?
Movement of plates in the earth’s crust caused the Fall Zone granite to pull and twist, resulting in stress lines and cracks. You can get a sense of this by twisting the skin on your (or your friend’s) forearm. The cracks in the granite of the James River are tiny in comparison to the vastness of the earth’s plates.

cracks in granite

Digging Deeper

The earth’s surface is divided into TECTONIC PLATES that are approximately 113 km (70 mi) thick. The land we live on, the continental crust, and the land   that is under the ocean, the oceanic crust, are part of these plates.

Tectonic plates are constantly moving, and, when they bump together or slide past one another, they cause earthquakes. Right now, the plates under the Atlantic Ocean are spreading, causing America and Europe to move away from one another.

tectonic plates

Map of Earth's tectonic plates

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