Top of the basalt columns showing the classical hexagonal shapes, f...
By Volcano Hazards Program
2007 (approx.)
Detailed Description
These glacial striations are carved in the top of a columnar-jointed basalt lava flow. The lava flow was erupted between 200,000 and 100,000 years ago in the Middle Fork of the San Joaquin River valley. The lava flow was then eroded during subsequent glacial periods, as shown by the finely polished and deeply striated surface.
Sources/Usage
Public Domain.
unknown USGS source
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Related
Vertical columns of volcanic rock at Devils Postpile National Monument
A spectacular display of a columnar-jointed basalt flow.
Glacial Features in the Long Valley Area, California
Glaciers have played an important role in modifying the landscape of the Long Valley area before, during, and after the enormous caldera-forming eruption 760,000 years ago.