Dry Falls, Washington
Dry Falls
Interesting facts
- At the height of the floods the cliff lay beneath about 300 feet of water rushing towards it at an estimated 65 miles per hour.
- Each outburst of glacial Lake Missoula may have released energy equal to about 4,500 megatons of TNT, some 90 times the largest nuclear bomb ever tested.
- The floods recurred between roughly 15,000 and 13,000 years ago, with the lake filling and emptying on a cycle averaging about 55 years.
- Together the floods scoured an estimated 210 cubic kilometres of soil, sediment and basalt from the Channeled Scablands and carried it downstream.
- J Harlen Bretz coined the name Channeled Scablands in 1923, and his flood theory sparked a bitter debate among geologists that lasted some forty years.
- At a 1927 meeting in Washington, D.C., Bretz faced a panel of established geologists presenting rival theories, an event he regarded as an ambush.
- Bretz received the Penrose Medal, the highest honour of the Geological Society of America, in 1979 at the age of 96.
- A plaque honouring Bretz was dedicated in 1994 outside the visitor centre on the rim of the falls.
- Below the falls stands Umatilla Rock, a large mass of basalt that withstood the floods while the rock around it was torn away.
- The stone lookout on the rim, Vista House, was built in 1938 by the Civilian Conservation Corps.
Why it is worth it
Dry Falls is the skeleton of what was once one of the greatest waterfalls on Earth: a scalloped basalt cliff about 3.5 miles (5.6 km) wide and 400 feet (120 m) high in the Grand Coulee of central Washington. Where the water once poured over its four great alcoves there are now only dark rock walls and small lakes in the plunge pools below, set in a landscape that looks freshly scoured.
The cliff was carved by the Missoula floods at the end of the last ice age. A lobe of the continental ice sheet dammed the Clark Fork River in present-day Montana, creating glacial Lake Missoula; each time the ice dam failed, the lake emptied across eastern Washington in a matter of days, and as it refilled the cycle repeated, probably forty or more times. At the height of a flood the waterfall at this point is estimated to have been about five times the width of Niagara Falls, carrying ten times the combined flow of all the rivers in the world today. The torrents stripped the soil from the plateau and cut the maze of dry channels known as the Channeled Scablands.
This explanation was first proposed in the 1920s by the geologist J Harlen Bretz, and for decades it was rejected because catastrophic floods contradicted the gradualist thinking of geology at the time; landscapes like Dry Falls eventually helped to vindicate him. The cliff is protected within Sun Lakes-Dry Falls State Park, whose interpretive centre on the rim explains the floods. Above the falls, the upper Grand Coulee is now filled by Banks Lake.
Getting there
Dry Falls lies in Grant County, Washington, a few kilometres south-west of Coulee City, on Washington State Route 17. The nearest larger city is Moses Lake, about 53 km away in a straight line. The nearest airport is Pangborn Memorial Airport (EAT) at East Wenatchee, about 68 km away.
On these lists
From the encyclopaedia
Dry Falls is a 3.5-mile-long (5.6 km) scalloped precipice with four major alcoves, in central Washington scablands. This cataract complex is on the opposite side of the Upper Grand Coulee from the Columbia River, and at the head of the Lower Grand Coulee, northern end of Lenore Canyon. According to the current geological model, catastrophic flooding channeled water at 65 miles per hour through the Upper Grand Coulee and over this 400-foot (120 m) rock face at the end of the last glaciation. It is estimated that the falls were five times the width of Niagara Falls, with ten times the flow of all the current rivers in the world combined.
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