An unnamed arch west of Trout Lake,
Photo by Jay Wilbur
Example Lava Natural Arch
NABSQNO 10T-603996-5090525. This unnamed arch is one of a series of lava natural arches that were formed due to the collapse of most of the roof of a large lava tube. This tube and its arches are located a few miles west of the town of Trout Lake, Washington, in the Gifford Pinchot National Forest. Although there is a stream that now runs through the old lava tube, it is clear that flowing lava created the subterranean passageway rather than water. Roof collapse then completed the formation of the arches. Thus, this feature must be considered a lava natural arch rather than a natural bridge, even though it spans flowing water.
Other Lava Natural Arch examples:
© 2003 by Jay H. Wilbur,
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