Parting of the Waters, Two Ocean Pass
Early travelers to the area that became Yellowstone National Park found fish were abundant in the Yellowstone River and Lake and their tributaries, but many other lakes and streams were devoid of fish. At first, people thought heat and chemicals from geothermal features killed fish in some places. Then geologists offered another explanation.
The Yellowstone plateau, geologists said, was a huge sheet of volcanic rock left by a super volcano. Across eons, a giant glacier formed over the volcanic rock. When the ice age ended, the glacier melted washing away soft material but leaving hard volcanic rock. This formed a circle of waterfalls and cascades that fish couldn’t get over to populate the plateau.
The geologists’ theory explained the fishless waters, but it left a deeper mystery: How did fish get into upper Yellowstone and its tributaries? Certainly, they didn’t do it by…
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