The James River Park System - Richmond, VA

5 of 10 • start over

North Geology Tour

Stop 5b: Raging Rapids

DIRECTIONS: If the river is low, descend the ramp and explore the rocks. If the river level is high, investigate rocks near the shoreline. DO NOT attempt to jump the channels. Colorless patches of single-celled algae makes slips and falls almost inevitable. Look for POTHOLES, round holes in the granite. (37.52990° N, 077.45440° W)

POTHOLES are created when small pebbles and sand get caught in granite cracks. As water floods through the cracks, the pebbles grind against the granite creating a small hole. As larger rocks are swept into the cavity, they grind out a bigger hole. This process is known as ABRASION. These holes were formed over thousands of years.

potholes

Aerial image showing potholes in the granite bedrock; scale of picture is about 2,500 square meters (26,910 square feet) right photo

Feel the sides of the pothole. BE CAREFUL of broken glass. The sides of the pothole are smoothest near the bottom where more recent carving has taken place. Note that stones remaining in the hole have rounded edges from the grinding process.

Potholes continue to grow when the river floods. Do not remove any stones, as this would end development of the pothole and ruin the experience for other visitors.


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