
Broken Bedrock
Posted by:
Volcanoguy
N 42° 58.330 W 120° 46.656
10T E 681229 N 4760120
Quick Description: Two of the four signs at this kiosk at the Summer Lake Rest Area.
Location: Oregon, United States
Date Posted: 9/30/2007 5:25:25 PM
Waymark Code: WM2A48
Views: 21
Long Description:This kiosk is located at the Summer Lake Rest Area. There are four signs in the kiosk: Broken Bedrock (geology), Fremont Arrives (History), Local Attractions, and Byway Description
Marker Name: Broken Bedrock
Marker Text: Less than a half mile from here, Summer Lake spans the tranquil expanse of this basin and Winter Ridge rises majestically to its west - no one would suspect this land’s tumultuous past.
Summer Lake was formed by tectonic forces that pushed and twisted this landscape into ridges and valleys over the past 10 million years. Winter Ridge, rising to the west of the lake, is Summer Lake’s “fault scarp.” Millions of years ago, the bedrock of the ridge and the bedrock underlying the lake were pushed together. The lakebed sank, and the bedrock split along a north-south fault line, and Winter Ridge rose, forming a steep slope - a scarp - between the two faults
Summer Lake was once part of enormous Chewaucan Lake, which has periodically occupied this part of the Great Basin over the past three million years. As Chewaucan Lake dried, starting around 10,000 years ago, it exposed lake bottom sediments. Blown by desert winds, these ancient sediments form the sand dunes that lie on the east side of today’s Summer Lake.
Comment - It is obvious that no geologist was involved in writing this sign. The Basin and Range province is the result of extensional forces not compressional forces as the sign implies.
Marker Name: Fremont Arrives
Marker Text: Summer Lake and Winter Ridge were both named in 1843 by Captain John C. Fremont, leader of a US Army Topographical Corps expedition whose ambitious goal was to explore and map the Great Basin lands of eastern Oregon, Nevada, and Utah.
On December 16, 1843, Fremont and his party stood shivering and windblown atop the steep ridge just southwest of here. Peering down through the cold air to the sunny lake below, the explorers were instantly inspired: “... we found ourselves on the verge of a vertical and rocky wall of the mountain. At our feet ... more than a thousand feet below ... we looked into a grass prairie country, in which a beautiful lake, some twenty miles in length, was spread along the foot of the mountain ... Shivering on snow three feet deep, and stiffening in a cold north wind, we exclaimed at once that the names of summer lake and winter ridge should be applied to these proximate places of such sudden and violent contrast.” Captain John C. Fremont, December 16, 1843
Propelled to the national stage by his achievements at western exploration, Fremont was nominated as the Republican candidate for President in 1856; later, he served in the Civil War, advancing to the rank of major-general.
Fremont died in 1890, but the many names that he applied to the local landscape - Abert Rim, Winter Ridge, Summer Lake - persist. Indeed, the term “Great Basin” itself was coined by Fremont, who noticed that the rivers of this basin-and-range country converged in lakes, but did not empty into the sea.
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