Pangea Ultima: Earth in 250 Million Years? Credit & Copyright: C. R. Scotese (U. Texas at Arlington)
Evolution fascinates me, not just because it presents a compelling story about how live changes, but because everything changes. It’s not just life – it’s rock, elements, stuff like that. Finally understanding that even nonliving matter was subject to these forces shifted my thinking slantwise. The fish with legs mental image was finally superseded by a picture of the slow motion churn of continental plates creaking under pressure.
Our mayfly-like perspective is, once again, an obstacle in the way, so here’s a YouTube video:
A Crash Course
An old NASA article provided a rather clumsy article describing plate tectonics. But, it did have a few really cool pictures. Why not ravage them and use the far more approachable “Plate tectonics 101 for the layman” found at Nyiwin’s Blog.
Although the world seems to be solid, continuous and stationaly, it is actually moving relative to one another. The whole earth mass once was in continuity and it is called Pangaea which existed about 250 million years ago
The world is made up of large plates of solidified larva that sort of float on the still fluid magma deep inside the earth and move relative to the adjacent ones. At the edge of the adjacent plates which move horizontally in opposite directions, different directional forces move the adjacent plates but as they are locked in contact and cannot move freely, great tension developed at their contact edges which, when it exceeds the resistance that is holding the adjacent margins of the plates together, slip a little and then lock up again at another point until the pressure builds up to cause it to slip again. Earthquakes occur when the slip happens and when the resistance that hold the 2 plates is great, large tension will be required before it slips and if it do, the slip will be greater and the magnitude of the earthquake will be so too.
The Pacific ring of fire, the eastern margin which includes the west coast of the USA is an example. That is also why Indonesia has frequent earthquakes and tsunamis, and also many volcanoes which result from seepage of magma at the edge weak point there and also on the west coast of S. America. (Nyiwin)
The post’s author continually apologizes for his ignorance, but does a really good job keeping things understandable. It’s far more interesting than the dry stuff you’ll read at Wikipedia. If you care, even a little, about this constant, slow-motion, earthly plate-scraping, then give it a read.
