AboutKeith Patton Expertise I can answer questions concerning physical and historical geology, environmental geology/hydrology, environmental consulting, remote sensing/aerial photo interpretation, G&G computer applications, petroleum exploration, drilling, geochemistry, geochemical and microbiological prospecting, 3D reservoir modeling, computer mapping and drilling.I am not a geophysicist.
Experience I have 24 years experience split between the petroleum and environmental industries. I have served as an expert witness in remote sensing, developmental geologist, exploration geologist, enviromental project manager, and subject matter expert in geology and geophysical software development.
Organizations American Association of Petroleum Geologists
American Association of Photogrammetrists and Remote Sensing
Education/Credentials Bachelor and Master of Science
Registered Geologist in State of Texas
Question Let's jump into a time machine and go back to the Carboniferous Period as Pangaea was forming. The Appalachian Mountains and the Ouachita Mountains were being uplifted by extreme forces as the years slowly passed by. During the maximum force of continental impact, before the continents began to pull away from each other, what did the areas of Alabama, Mississippi, Arkansas and Tennessee look like as far as mountain ranges go?
To be more specific:
1) Did these two mountain ranges ever meet?
2) If so, where?
3) How high did they get in this area? Rocky Mountain or Himalaya high?
4) Was this a continuous mountain range or did it have low lying areas running through it?
5) Where, if they were overlaid on a current map of the Southern U.S., did these two ranges hit their maximum height and what routes did they follow?
I'm hoping you can answer these questions, as I have been unable to uncover the answers. I would also greatly appreciate any links that might show topographical maps of the area in question during that period of time.
Thanks.
Answer Mike,
First, the Carboniferous only saw the formation of the Southern Appalachians and the Ouachitas. The rest of the Appalachians came later as a result of no fewer than "three separate continental collisions involving the North American Continent with the Taconic and Acadian terranes, and finally the collision of the African and North American continents during the Alleghenian Orogeny at the end of the Paleozoic". (USGS)
The Ouachitas were uplifted by compression due to subduction along the Laurentia and South American continental plates.
The formation of the Applachians was very complex. I went to school in Virginia and hiked and studied just that portion of the chain. I lived in Oklahoma and was able to hike and canoe in the Ouachitas. The difference in the mountains is remarkable. The geology of the appalachians are pretty complex and were the prime example for the Geosynclinal theory of mountain building which predated plate tectonics. You can see all the different facies, that were used to formulate the theory. There was a lot of arm waving back then (late 60's early 70's) trying to explain what caused the uplifts and deformtion of the sediments laid down in the depositional basins. Plate tectonics tied it all together nicely. I began my studies when plate tectonics was still considered by some as an interesting idea.
If one uses a crude straight measurement of the folds in the Appalachians, you could assume they got Himalyas high, but one has to take into account the concurrent erosion. One must also take into account presence or absence of terrestrial vegitation. In some epochs lack of terrestrial vegitation would have meant much higher rates of erosion. It is estimated that the Appalachians got as high as the Andes, 13000 feet or 3600 m.
The mountains formed not from south to north, nor north to south, but in various places along the present mountain belt in pulses as various parts collided as the different plates impinged on one another. Remember subduction was occurring along the east coast so anything lying to the east eventually collided with NA.
420 mya Silurian, the Taconic terrain impacted along what is now NY raising the NY Bight region.
370 mya Late Devonian the Avaion Terrain, formerly an off shore island arc similar to Japan to day, impacted New England, to the west the Catskill delta was forming.
320 mya Late Miss Pangea itself impinged on NA causing the Alleghenian orogeny. Pangea itself had formed.
290 mya Late Penn. Climax of Alleghenian orogeny continued compression of the joined plates caused fold belts to form,
250 mya Late Permian Orogenic activity nil, erosion of uplifted heights taking place.
