Atlantis Online
May 21, 2019, 02:32:11 pm
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Scientists Confirm Historic Massive Flood in Climate Change
http://www.giss.nasa.gov/research/news/20060228/
 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

the Mid-Atlantic Ridge (Original)

Pages: 1 2 3 4 [5] 6 7 8 9 10   Go Down
  Print  
Author Topic: the Mid-Atlantic Ridge (Original)  (Read 9621 times)
Carolyn Silver
Superhero Member
******
Posts: 4611



« Reply #60 on: July 28, 2008, 11:37:28 pm »


Figure 5. A plot of rock age vs. distance from the crest of the Mid-Atlantic Ridge. (Reprinted with permission from Meyerhoff et al., 1996a, fig. 2.35. Copyright by Kluwer Academic Publishers.)

    The numerous finds in the Atlantic, Pacific, and Indian Oceans of rocks far older than 200 million years, many of them continental in nature, provide strong evidence against the alleged youth of the underlying crust. In the equatorial segment of the Mid-Atlantic Ridge numerous shallow-water and continental rocks, with ages up to 3.74 billion years have been found. A study of St. Peter and Paul's Rocks at the crest of the Mid-Atlantic Ridge just north of the equator, turned up an 835-million-year rock associated with other rocks giving 350-, 450-, and 2000-million-year ages, whereas according to the seafloor-spreading model the rock should have been 35 million years.
    Rocks dredged from the Bald Mountain region just west of the Mid-Atlantic Ridge crest at 45°N were found to be between 1690 to 1550 million years old. 75% of the rock samples consisted of continental-type rocks, and the scientists involved commented that this was a 'remarkable phenomenon' -- so remarkable, in fact, that they decided to classify these rocks as 'glacial erratics' and to give them no further consideration. Another way of dealing with 'anomalous' rock finds is to dismiss them as ship ballast. However, the Bald Mountain locality has an estimated volume of 80 km³, so it is hardly likely to have been rafted out to sea on an iceberg or dumped by a ship! In another attempt to explain away anomalously old rocks and anomalously shallow or emergent crust in certain parts of the ridges, some plate tectonicists have put forward the contrived notion that 'nonspreading blocks' can be left behind during rifting, and that the spreading axis and related transform faults can jump from place to place.
    Strong support for seafloor spreading is said to be provided by marine magnetic anomalies -- approximately parallel stripes of alternating high and low magnetic intensity that characterize some 70% of the world's midocean ridges. According to the plate-tectonic hypothesis, as the fluid basalt welling up along the midocean ridges spreads horizontally and cools, it is magnetized by the earth's magnetic field. Bands of high intensity are believed to have formed during periods of normal magnetic polarity, and bands of low intensity during periods of reversed polarity. However, ocean drilling has seriously undermined this simplistic model.
    Correlations have been made between linear magnetic anomalies on either side of a ridge, in different parts of the oceans, and with radiometrically-dated magnetic events on land. The results have been used to produce maps showing how the age of the ocean floor increases steadily with increasing distance from the ridge axis. As indicated above, this simple picture can be sustained only by dismissing the possibility of older sediments beneath the basalt 'basement' and by ignoring numerous 'anomalously' old rock ages. The claimed correlations have been largely qualitative and subjective, and are therefore highly suspect. More detailed, quantitative analyses have shown that the alleged correlations are very poor. A more likely explanation of the magnetic stripes is that they are caused by fault-related bands of rock of different magnetic properties, and have nothing to do with seafloor spreading.

Report Spam   Logged
Pages: 1 2 3 4 [5] 6 7 8 9 10   Go Up
  Print  
 
Jump to:  

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