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In the oceans, species don't have to deal with whole changes in the physical characteristics of their ecosystem.
As we will discuss later, the earth currently has significant climate variations on a timescale of 100,000 years. In addition, over the last 200-250 million years the earth is experiencing an era go global tectonic motion which makes the land surface a Dangerous Place to Live:
Summary of Evidence for Plate Tectonics:
Now it is recognized that the surface of the earth can be divided up
into roughly 10--12 large scale plates
and perhaps a number of smaller ones as in the case of the
Pacific Northwest
could just mean that the climates and hence vegetation and animal
life were similar
this
is much harder to explain away especially if the ages of the rock
types are similar.
Magnetic mapping of the ocean floor revealed
a history of polarity reversals that formed a mirror image about
the Mid-Atlantic Ridge. This indicates that the floor of the Atlantic
Ocean is created at the mid Atlantic ridge due to crustal separation.
As magma issues forth and solidifies, it records the orientation of
the earth's magnetic field at the time of solidification. These
newly formed rocks are then carried either East or West of the
Mid-Ocean ridge. The floor of the Atlantic Ocean is thus an Age
sequence with newly formed rock appearing at the Mid Atlantic Ridge and
the oldest rocks being at the North American and European Coastlines.
The time of transport from the mid Atlantic ridge to these coastlines
is about 210 million years which indicates a total sea floor motion of
about 1.5 inches per year.
The earth's crust is actually a two-component layer. The lithosphere is a thin layer of rock (average density of 2.7 grams per cc) and "floats" on top of a plastic-like layer called the asthenosphere. Plastic-like materials are weird - they deform under stress but don't really break. A glacier is a good example of a material that moves and flows plastically. The convective heat currents in the mantle impinge on the asthenosphere causing deformation and subsequent movement of the lithospheric plates.
This process can be simulated in your kitchen by putting some jello in a bowl and putting some peebles on top of the jello. As you shake the bottom of the bowl, the jello deforms but doesn't break and the rocks that float on the jello collide. (apologies to real geologists for this analogy).
As a result of plate movements, interesting things occur at plate boundaries. In general you don't want to live near a plate boundary as the earth is active there. About 75% of the world's population does live near these boundaries.
There are three types of plate boundaries:
Local Manifestations of Plate Tectonics:
Some Other Internet Resources on Plate Tectonics: