Atlantis Online
March 28, 2024, 04:24:35 am
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Underwater caves off Yucatan yield three old skeletons—remains date to 11,000 B.C.
http://www.edgarcayce.org/am/11,000b.c.yucata.html
 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

Can a Continent Sink?

Pages: [1] 2 3 4 5   Go Down
  Print  
Author Topic: Can a Continent Sink?  (Read 7370 times)
0 Members and 26 Guests are viewing this topic.
Adam Hawthorne
Superhero Member
******
Posts: 4250



« on: April 08, 2007, 11:31:57 pm »

History

Before geology, the presence of mountains was explained in Christian contexts as a result of the Biblical Deluge, for Neoplatonic thought, which influenced early Christian writers, assumed that a perfect Creation would have to have been in the form of a perfect sphere. Such thinking persisted into the eighteenth century.

Orogeny was used by Gressly (1840) and Thurmann (1854) as orogenic in terms of the creation of mountain elevations, as the term mountain building was still used to describe the processes.

Elie de Beaumont (1852) used the evocative "Jaws of a Vise" theory to explain orogeny, but was more concerned with the height rather than the implicit structures orogenic belts created and contained. His theory essentially held that mountains were created by the squeezing of certain rocks.

Suess (1875) recognised the importance of horizontal movement of rocks. The concept of a precursor geosyncline or initial downward warping of the solid earth (Hall, 1859) prompted Dana (1873) to include the concept of compression in the theories surrounding mountain-building. With hindsight, we can discount Dana's conjecture that this contraction was due to the cooling of the Earth (aka the cooling earth theory).

The cooling Earth theory was the chief paradigm for most geologists until the 1960s. It was, in the context of orogeny, contested hotly by proponents of vertical movements in the crust (similar to tephrotectonics), or convection within the asthenosphere or mantle (geology).

Steinmann (1906) recognised different classes of orogenic belts, including the Alpine type orogenic belt, typified by a flysch and molasse geometry to the sediments; ophiolite sequences, tholeiitic basalts, and a nappe style fold structure.

In terms of recognising orogeny as an event, Leopold von Buch (1855) recognised that orogenies could be placed in time by bracketing between the youngest deformed rock and the oldest undeformed rock, a principle which is still in use today, though commonly investigated by geochronology using radiometric dating.

Zwart (1967) drew attention to the metamorphic differences in orogenic belts, proposing three types, modified by Pitcher (1979);

Report Spam   Logged


Pages: [1] 2 3 4 5   Go Up
  Print  
 
Jump to:  

Powered by EzPortal
Bookmark this site! | Upgrade This Forum
SMF For Free - Create your own Forum
Powered by SMF | SMF © 2016, Simple Machines
Privacy Policy