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Science in the Park: Rock Pools

The granite bedrock surrounding Belle Isle contains many variations of a fascinating geologic feature: the pothole or rock pool. These round and oval holes are caused by the grinding action of gravel or stones that lodge in the cracks of rocks during floods. As the pebble is vibrated by the current, it grinds down the stone around it, eventually creating a hole that can be a microcosm for ecological processes.

Note the different locations and shapes of the rock pools, and investigate the plant and animal life that inhabits them. Each one is a world of its own!

James RIver Rock Pools

Plants of the rock pools

Rock pools – also called potholes – are holes in the granite riverbed caused by the grinding action of gravel and stones during floods, or by the actions of man. Plants that thrive in and around them are uniquely adapted for their unusual, and often changeable and challenging, setting. Explore these fascinating specimens.

Plants of the Rock Pools Introduction (PDF)
Complete Plants of the Rock Pools Guide (PDF)
Lesson Plan – Species Biodiversity Lab (PDF)

Woody plants invest energy in growing strong trunks or stems to lift their leaves to the sunlight. In this Fall Zone environment, they are more stunted than their counterparts on the banks, often having multiple trunks, with trees tending to look like shrubs.

Vines are plants with long, flexible stems that climb over other plants and objects as they grow. This strategy enables them to reach sunlight without investing large amounts of energy and resources in tall, strong stems.

Aquatic plants grow in and around the rock pools and slow channels of the river. Some are rooted in mud or cracks in the rocks; others float on, or near, the water surface. They tend to be soft, fleshy, and easily torn.

Wildflowers are herbaceous plants of moist to dry conditions. Soft-stemmed perennials or annuals, they grow in silt that collects around the edges of rock pools or in the sand and soil that accumulates between rocks.

Rooted in the mud or sand around the rock pools are flowering plants with grass-like leaves ranging in size from 4 inches to 3 feet high. Long, slender, leaf blades growing out of a basal clump largely define the character of a grass.

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