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Columnar joints in the basalt flow at Grand Falls

Columnar joints in the basalt flow at Grand Falls
Columnar joints in the basalt flow at Grand Falls This is one of the more ordered sets of joints; in many places there is no clear texture to the rock, suggesting complicated interactions with water as the lava cooled. Note that the normally-black basalt is stained tan-colored by the silt-bearing mist from the falls, yet more evidence that they are constantly eroding the rock that they flow over. Ryan Anderson