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Posted By:
Hal Brown
Date Posted:
Oct 24, 2008
Description:
The flight schedule had to be mostly business. Peli’s suitor was waiting in Little Rock. I was bound to be there by noon. After Fort Smith, I had to leave the river and go direct towards Little Rock to make up for earlier splashing, er…I mean hull washing.
Leaving the river took me into the Ouachita Mountains. “Mountains in Arkansas? In the middle of the continent? How did that happen?” one might ask.
Mountains out in the middle of the country have surprised more than a few unlucky aviators. There are plenty of planes that have collided with the peaks. After all, why would anyone expect mountains in the middle of the country?
Well, as is theorized by geologists, Arkansas was not always in the center of the continent. Way back in Paleozoic time (Ordovician to Mississippian periods), a deep ocean placidly collected sediments in this area.
This ocean had the misfortune to be located between the North and South American tectonic plates. During Mississippian time the plates started to converge. The North American plate got pushed under the over-riding South American plate.
All this colliding and pushing of the plates deformed the formerly uniform sediments. Contrary to governmental policy, they were bent, folded and generally mutilated. They were also pushed upwards in what became the Ouachita orogeny in late Pennsylvanian and Permian time. The folded mountains that resulted were as tall as the Rockies.
Some of the tilted sediments were clearly present in a road cut right through a small ridge. It is notable that volcanism, metamorphism and intrusion are mostly absent in these mountains.
All the continental shifting caused the area around Arkansas, parts of Oklahoma, and southern Kansas to generally be lifted upwards during Mesozoic time. Anytime there is uplift, gravity and water do their best to bring everything back down to earth. Erosion stripped away the least resistant rocks first, leaving the ZigZag Mountains.
Along with the Ozark Mountains to the north, the Ouachita Mountains are part of the U.S. Interior Highlands physiographic region. This is the only mountainous region between the Appalachian and the Rockies.
Date Taken:
Oct 24, 2008
Place Taken:
Near Bonanza, AR
Owner:
Dan Nickens
File Name:
7_Ridge_Cut.jpg - Photo HTML
Full size - <img src="/show.php?splash=SZT270000h">
Medium - <img src="/show.php?splash=SZT270000m">
Thumbnail - <img src="/show.php?splash=SZT270000s">
Category:
329, Taking Peli Home
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