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quote:Originally posted by JDG8R (snip)For this topic, and a myriad of others, what is your general feel toward catastrophism? I am convinced (by watching tv on the subject I am not ashamed to admit--well sort of) that certain very large (1000's of square mile)erosion features happen relatively quickly (The one on tv was one probably famous to you, somewhere in Montana I think).
quote:What is the greatest elevation change of any mountian range that has been observed in the last 500 years? Does that extrapolate to anywhere near the 14,000 feet in elevation over what ever the age of the rockies are or to the 29,000 feet over the age of the Himalyayas?
quote:Originally posted by JimBobThis is the Washington-0regon scab lands you are thinking of. They were formed by Lake Agassiz, a ice-plugged lake of huge area on the Columbia River.
quote:Originally posted by OphioliteJDC - The growth of the Rocky Mountains has been one of the most perplexing of geologic puzzles. Normally, mountain building is focused between 200 to 400 miles inland from a subduction zone boundary, yet the Rockies are hundreds of miles farther inland. What geologic processes raise mountains at this scale? Although geologists continue to gather evidence to explain the rise of the Rockies, the answer most likely lies with an unusual subducting slab. At a 'typical' subduction zone, an oceanic plate typically sinks at a fairly high angle (see above). A volcanic arc grows above the subducting plate. During the growth of the Rocky Mountains, the angle of the subducting plate may have been significantly flattened, moving the focus of melting and mountain building much farther inland than is normally expected. It is postulated that the shallow angle of the subducting plate greatly increased the friction and other interactions with the thick continental mass above it. Tremendous thrusts piled sheets of crust on top of each other, building the extraordinarily broad, high Rocky Mountain range.Source: newbielink:http://wrgis.wr.usgs.gov/parks/province/rockymtn.html [nonactive]Observe; collate; conjecture; analyse; hypothesise; test; validate; theorise. Repeat until complete.