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> Guess how a shark tooth winds up buried in Montana? My guess is plate tectonics. https://en.wikipedia.org/wiki/Plate_tectonics https://en.wikipedia.org/wiki

by fiter 10y ago

> Guess how a shark tooth winds up buried in Montana? My guess is plate tectonics. https://en.wikipedia.org/wiki/Plate_tectonics https://en.wikipedia.org/wiki/Plate_tectonics

sathackr 10y ago
While it is widely accepted that portions of the Rocky Mountains were once underwater, and were pushed up via orogenic processes, it is also widely accepted that the vast majority of the central United States spent a significant amount of time underwater due to a higher global sea level. Since this trough only covers the western 1/4 or so of Montana[2], I think it would be safe to say that, on average, a shark tooth found in Montana was not found in an area of orogenic lifting, thus was likely deposited there by a shark, or something higher on the food chain than a shark, during a period in which the sea levels were much higher than they are today. Are there places in Montana where orogenic lifting created dry land? Yes. Are they as likely to be trafficked by humans as the others? No. I suppose they could also have been recently deposited by a migratory bird. [1] http://pubs.usgs.gov/gip/continents/ http://pubs.usgs.gov/gip/continents/ [2] http://pubs.usgs.gov/gip/continents/cretaceous.jpg http://pubs.usgs.gov/gip/continents/cretaceous.jpg
- fiter 10y ago
  Sorry it took me so long to see that you responded! I looked up the elevations of cities in Montana and it looked like the minimum was 2000 ft. This implies that we've seen more change due to plate tectonics than the 750 ft (generous) sea level change. [0] Granted, to really resolve the argument on the shark's tooth we'd have to know how deep that shallow sea was in the Cretaceous Period. On the positive side, even if sea levels rose 750 ft now, Montana wouldn't be underwater. :) [0] http://www.open.edu/openlearn/ocw/pluginfile.php/69982/mod_oucontent/oucontent/522/05884163/5a6419c8/sxr260_1_004i.jpg http://www.open.edu/openlearn/ocw/pluginfile.php/69982/mod_o...

by fiter 10y ago

> Guess how a shark tooth winds up buried in Montana? My guess is plate tectonics. https://en.wikipedia.org/wiki/Plate_tectonics https://en.wikipedia.org/wiki/Plate_tectonics

sathackr 10y ago

While it is widely accepted that portions of the Rocky Mountains were once underwater, and were pushed up via orogenic processes, it is also widely accepted that the vast majority of the central United States spent a significant amount of time underwater due to a higher global sea level. Since this trough only covers the western 1/4 or so of Montana[2], I think it would be safe to say that, on average, a shark tooth found in Montana was not found in an area of orogenic lifting, thus was likely deposited there by a shark, or something higher on the food chain than a shark, during a period in which the sea levels were much higher than they are today. Are there places in Montana where orogenic lifting created dry land? Yes. Are they as likely to be trafficked by humans as the others? No. I suppose they could also have been recently deposited by a migratory bird. [1] http://pubs.usgs.gov/gip/continents/ http://pubs.usgs.gov/gip/continents/ [2] http://pubs.usgs.gov/gip/continents/cretaceous.jpg http://pubs.usgs.gov/gip/continents/cretaceous.jpg

fiter 10y ago
Sorry it took me so long to see that you responded! I looked up the elevations of cities in Montana and it looked like the minimum was 2000 ft. This implies that we've seen more change due to plate tectonics than the 750 ft (generous) sea level change. [0] Granted, to really resolve the argument on the shark's tooth we'd have to know how deep that shallow sea was in the Cretaceous Period. On the positive side, even if sea levels rose 750 ft now, Montana wouldn't be underwater. :) [0] http://www.open.edu/openlearn/ocw/pluginfile.php/69982/mod_oucontent/oucontent/522/05884163/5a6419c8/sxr260_1_004i.jpg http://www.open.edu/openlearn/ocw/pluginfile.php/69982/mod_o...