Tuesday, March 10, 2015

The Edge of the Rockies - Eastern Washington Steptoes

The Rocky Mountains do extend into the east edge of Washington State. High mountains that are part of the complex ranges of the Rockies are located in the northeast part of the state. South of Spokane the range is more subdued, but outliers that reach above the Columbia River Basalts and rise above the silt deposits of the Palouse crop out as isolated peaks.

Steptoes in the Palouse

Steptoe Butte is the most famous and that butte lends its name to similar types of buttes that rise above the much younger deposits.

Steptoe Butte viewed from the northwest rises above the Palouse

Steptoe Butte and its lesser steptoes to the north consist of very ancient Precambrian bedrock of the Revett and Burke Formations. Formations found to the east in the Rockies.

Two other outcrops of Precambrian rocks are located in the canyon of Rock Creek east of the steptoes. Both of these Precambrian outcrops are highly metamorphosed and their affinity is uncertain (see bonnie-lake-precambrian-schist and more-notes-on-bonnie-lake-steptoe).

To the northeast of Cheney and extending to Reardon are another set of steptoes most of which are Precambrian outcrops correlated with other Precambrian rocks to the east and north.

These steptoes also were along the upper part of the Palouse floodway path that was flooded during the larger ice-age floods. The peaks stood above the flood waters. Would have been a good place to watch the flood pass by if one was lucky enough to be on one of these steptoes. Interstate 90 passes between Wrights Hill and Riddle Hill and one can get a glimpse of the ancient rocks along the freeway.

Steptoe Butte was named for Colonel Steptoe. Steptoe and most of his men were nearly slaughtered by a unified group of Indians led by Chief Kamiakin near the Butte that now has his name (he did not however use the butte as a defensive location). Wrights Hill was named for General George Wright. He led U.S. troops in a retaliation strike against the Indians and from the hill that has his name his troops with better guns than the Indians badly defeated the consolidated tribes and brutally ended warfare in Washington Territory.    

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