Not by me, but by Wayne Ranney's Earthly Musings blog.
His visit was to southwestern Oklahoma, of the Fort Sill and Wichita Mountains area, visiting sites related to U.S. History and Geology on the same journey. The first "half" of his post is related to the latter-19th Century history of this U.S. Army fort. Interesting and thought-provoking. [BTW, my Dad's artillery unit spent part of its WWII training in early- to mid-1943 at Fort Sill.]
The Wichita Mountains are composed of Precambrian to Eocambrian igneous rocks (of which the Mount Scott Intrusive Suite forms a significant part) and Cambrian and Ordovician sedimentary rocks (north of the Meers Fault) (Price, 2014).
The igneous rocks are associated with magmatism during the formation of the "Southern Oklahoma Aulacogen" (SOA), late-Proterozoic to earliest-Paleozoic failed continental rifting of the supercontinent "Pannotia" (Price, 2014).
[In William D. Thornbury's classic "Principles of Geomorphology" (1968), Fundamental Concept 7 is: "Little of the Earth's topography is older than Tertiary and most of it no older than Pleistocene." From Thornbury (1968): "Ashley (1931) has made a strong case for the youthfulness of our topography. He believed that 'most of the world's scenery, its mountains, valleys, shores, lakes, rivers, waterfalls, cliffs, and canyons are post-Miocene ... "
Fundamental Concept 8 is: "Proper interpretations of present-day landscapes is impossible without a full appreciation of the manifold influences of the geologic and climatic changes during the Pleistocene." Without going into too much detail, just consider the effects of glaciation and inter-glaciation related changes in the Ultimate Base Level.]
[Please spend time on the above-linked Earthly Musings post.]
Additional References:
The "Basement-Cored Uplifts" associated with the Wichita Mountains (trending NW to SE) include the Arbuckle Mountains to the east and westward extend as far as the Uncompahgre Uplift in Colorado and Utah and is associated with the Ancestral Rocky Mountains. Essentially parallel to the north in Oklahoma and the Texas Panhandle is the Anadarko Basin.
Wayne's second "half" of the post is about the Wichita Mountains area as an "Exhumed Permian Landscape", i.e., what we see now is what was exposed, eroded, and then covered by Mesozoic and Cenozoic sedimentary rocks. And then exposed again by post-Cenozoic erosion.
In other words, in this setting, we are looking at late-Paleozoic landforms, adorned with numerous plants that have appeared in the fossil record and evolved during the Mesozoic and Cenozoic Eras. Quite thought-provoking.
Wayne's second "half" of the post is about the Wichita Mountains area as an "Exhumed Permian Landscape", i.e., what we see now is what was exposed, eroded, and then covered by Mesozoic and Cenozoic sedimentary rocks. And then exposed again by post-Cenozoic erosion.
In other words, in this setting, we are looking at late-Paleozoic landforms, adorned with numerous plants that have appeared in the fossil record and evolved during the Mesozoic and Cenozoic Eras. Quite thought-provoking.
[In William D. Thornbury's classic "Principles of Geomorphology" (1968), Fundamental Concept 7 is: "Little of the Earth's topography is older than Tertiary and most of it no older than Pleistocene." From Thornbury (1968): "Ashley (1931) has made a strong case for the youthfulness of our topography. He believed that 'most of the world's scenery, its mountains, valleys, shores, lakes, rivers, waterfalls, cliffs, and canyons are post-Miocene ... "
Fundamental Concept 8 is: "Proper interpretations of present-day landscapes is impossible without a full appreciation of the manifold influences of the geologic and climatic changes during the Pleistocene." Without going into too much detail, just consider the effects of glaciation and inter-glaciation related changes in the Ultimate Base Level.]
[Please spend time on the above-linked Earthly Musings post.]
Figure 1. Saddle Mountain, north of Wichita Mountains Wilderness. Public Domain image. Eocambrian Saddle Mountain Granite, Wichita Granite Group.
For a personal aside, I have my own perceived "Exhumed Landscape" story, on the Georgia Coastal Plain. [When the post is completed, it will be linked here.]
More on Exhumed Landscapes are here, here, and here. [Haven't read these, yet.]
More on Exhumed Landscapes are here, here, and here. [Haven't read these, yet.]
Additional References:
Ashley, G.H., 1931 Our youthful scenery, Bulletin Geological Society of America, vol. 42, pp. 537 - 546.
Price, J.D., 2014 The Mount Scott Intrusive Suite, Wichita Mountains, Oklahoma, in Igneous and Tectonic History of the Southern Oklahoma Aulacogen, Oklahoma Geological Survey Guidebook 38, pp. 299 - 318.
Suneson, N.H., 2019 Roadside Geology of Oklahoma, Mountain Press
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