Wegener's Evidence: Fit of the Continents

[kingwinner]

Wegener's Evidence for Continental Drift Hypothesis:

 

1. Fit of the Continents

-see world map indicating location of earth's earthquake epicentres <---can someone explain how this point relate the the subtitle "fit of the continents"? Thank you!

 

2. Location of Past Glaciations etc etc...

[Turtle]

___Most earthquakes occur at plate boundries. Four different conditions prevail at plate boundries; spreading, (where new crust is formed), & colliding plates which either subduct, strike-slip, or lock.

___Working back in time by evidence of new crust formed from ocean spreading centers places the continents back to previous conditions in which they joined.

___Etc. etc.. :hihi:

[kingwinner]

"Working back in time by evidence of new crust formed from ocean spreading centers places the continents back to previous conditions in which they joined."

 

How are the locations of earth's earthquake epicentres relate to the fit of the continents? Can you explain this part a bit further? :hihi:

[kingwinner]

A teacher told me to see the world map with locations of earthquake epicentres to visualize the fit of continents, that makes me really confused...

 

Is this the world map with location of earthquake epicentres? (yellow dots)

[Turtle]

___The quakes occur primarily at the plate boundries. Your map looks suspicious. For example it shows quakes on Austrailian continent & no quakes along the Pacific plate spreading center. What is the source for the map?

___To see part of the fit, visualize shrinking the Atlantic ocean until Africa & South America "fit" together. Not only do they fit, they have the same kinds of rocks on their coasts today. Does this help? :hihi:

[kingwinner]

___The quakes occur primarily at the plate boundries. Your map looks suspicious. For example it shows quakes on Austrailian continent & no quakes along the Pacific plate spreading center. What is the source for the map?

___To see part of the fit, visualize shrinking the Atlantic ocean until Africa & South America "fit" together. Not only do they fit, they have the same kinds of rocks on their coasts today. Does this help? :hihi:

-the source is http://quakes.earth.uq.edu.au/seis_maps/ (the bottom)

 

 

-so the locations of earthquake epicentres have absolutely nothing to do the fact that the continents fit, right? (It is also on the notes that I got from my teacher, which make me think that these two things have some realtionship!)

[Turtle]

-so the locations of earthquake epicentres have absolutely nothing to do the fact that the continents fit, right?

__Wrong. Sorry if my explanation led you to that conclusion. The continent's fitting edges have between them a tectonic plate boundry which is the spreading center type. Between Africa & South America, the spreading center is called the Atlantic Ridge (the rightmost long row of yellow dots on your map). Along this ridge, underwater volcanism is creating new crust which moves outward pushing the Americas West & Africa East. It is a continuous jerky process & generates earthquakes in the vicinity of active regions on the ridge.

___When the continents were joined millions of years ago, the spreading actually started on land & only when it proceded far enough apart did the ocean flow in. The same thing is currently happening in the Great Rift Valley of Africa; it will eventually split & fill with an ocean.

___The other sets of earthquakes are a consequence of the opposite edges of continents being pushed by spreading centers colliding with one another. The Himalaya mountains is a locked collision where the India plate crashed into Asian plate. The Cascade mountains where I live are volcanos formed from the Juan De Fuca plate subducting (diving under) the American plate. The San Andreas Fault in California is a strike slip tectonic plate collision. All create earthquakes as the collision progresses.

___I hope this clarifies it for you?

[kingwinner]

So basically, by examining the locations of earthquake epicentres (for example the mid-Atlantic Ridge region), we can see that the Atlantic ocean is spreading which spilts South America and Africa (the two continents which "fits" like jigsaw puzzle) throughout the past hundreds of millions of years, which gives one of Wegener's evidence of Continental Drift...right? :hihi:

[Turtle]

So basically, by examining the locations of earthquake epicentres (for example the mid-Atlantic Ridge region), we can see that the Atlantic ocean is spreading which spilts South America and Africa (the two continents which "fits" like jigsaw puzzle) throughout the past hundreds of millions of years, which gives one of Wegener's evidence of Continental Drift...right? :lol:

Correct. Expeditions to collect seafloor cores have corroberated the hypothesis as well as evidence for magnetic pole shifts over Earth's history. The discoveries of black-smokers & other spreading center phenomena further corroberate plate techtonic theory & have opened a new understanding into the extreme environments that life may thrive in. Science is always amendable. :hihi: :lol:

[Turtle]

___Here is a just released article on new discoveries on sea-floor spreading in the Pacific; very interesting stuff!

http://www.terradaily.com/news/tectonics-05zzzu.html

:evil:

[kingwinner]

Thank you Turtle

[Turtle]

Thank you Turtle

My pleasure. :hihi: