Dry Falls State Park

Those of you who pay attention to such things will know about the Missoula Flood. Since this is such a mind bogglingly large event, I will give a longer than usual quote from Wikipedia below the fold.

The Missoula Floods (also known as the Spokane Floods or the Bretz Floods) refer to the cataclysmic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. The glacial flood events have been researched since the 1920s. These glacial lake outburst floods were the result of periodic sudden ruptures of the ice dam on the Clark Fork River that created Glacial Lake Missoula. After each ice dam rupture, the waters of the lake would rush down the Clark Fork and the Columbia River, flooding much of eastern Washington and the Willamette Valley in western Oregon. After the rupture, the ice would reform, creating Glacial Lake Missoula again.

During the last deglaciation that followed the end of the Last Glacial Maximum, geologists estimate that a cycle of flooding and reformation of the lake lasted an average of 55 years and that the floods occurred several times over the 2,000-year period between 15,000 and 13,000 years ago. U.S. Geological Survey hydrologist Jim O'Connor and Spanish Center of Environmental Studies scientist Gerard Benito have found evidence of at least twenty-five massive floods, the largest discharging ≈10 cubic kilometers per hour (2.7 million m³/s, 13 times the Amazon River).^[1] Alternate estimates for the peak flow rate of the largest flood include 17 cubic kilometers per hour^[2] and range up to 60 cubic kilometers per hour.^[3] The maximum flow speed approached 36 meters/second (130 km/h or 80 mph).^[2]

As a result of this monstrous, repeated flooding, huge canyons were created. This dry river beds, call coulee, were later filled small lakes and streams to become the place you see above...Dry Falls State Park.

This place is a few miles south of Coulee City and filled with curious rock formations that were part of the land that was spared by the massive erosion of the water.

In other places, we see giant boulders. These were apparently stones that were trapped in ice and floated along with the gush of water and deposited in random places. This large "pebbles" are seen in lots of place in the region.

You can see from this cliff face that the rock is largely basalt. In the ensuing millenia, bits has broken off the face and formed a border of really large gravel.

In the damp weather I happened to arrive in, the moss and lichens were growing rampantly on the rock faces.

As you could see in the initial panorama, there are now lakes in the coulee. At least some of these are stocked with fish and folks were enjoying themselves trying to outsmart small fish. The small lake below had no fishermen, and also no wind, making an ideal reflection of the surrounding hills.