Hi Faith
I see we have actually gotten into evidence and descriptions now. That has to be a good thing all around. Like you I always thought of divergent boundaries as a PUSH thing. I even took some quite advanced Geology classes back in the 70s that still left me thinking that way.
What Jazz is saying actually makes a lot of sense though so I went googling myself to find some simple descriptions of what is going on. Here are a few that I found. They definitely agree with what Jazz has been saying.
This picture came from
This very informative site.
Note that the thickness of the crust at the divergent boundary is very thin so a PUSH from this point would be likely to result in some serious buckling I think.
Also check the
Rift Valley shown to the right. It clearly shows the pulling action by the way that the sides of the valley are constantly falling into the rift via faulting as the plates move apart.
This site is very simple to understand also. It shows the way that a rift valley forms at a divergent boundary
I think the issue here is that the rift valleys (particularly land based ones) at divergent boundaries have been observed to widen
prior to the emergence of magma.
Does this information help at all?
{ABE for some reason my thumbnail doesn't show up properly. It does still open the picture when you click to enlarge though}
{AdminBen: AbE: PurpleYouko, you were using the URL of the webpage, not the image, in the "thumb" dbCode. You need to use the URL of the image}
This message has been edited by PurpleYouko, 09-16-2005 10:08 AM
This message has been edited by AdminBen, 09/16/2005 10:22 AM