Glaciation of the earth during the last ice age (ending ~10,000 years ago) is th

Question

Glaciation of the earth during the last ice age (ending ~10,000 years ago) is the cause of some ongoing deformation of the North America continent interior today. Describe the phenomenon of glacial rebound, and the evidence of it occurring since the last ice age and still ongoing today. Explain how this phenomenon can be understood in the context of isostasy. Considering that glacial rebound likely is causing earthquakes in North America continental crust today, and that seismic wave propagation occurs through the crust and mantle, why would we then conclude that the asthenospheric mantle behaves as an elasticviscous solid and the lithospheric mantle and crust behave as an elastic-plastic solid.

Explanation / Answer

Isostacy states that the equilibrium exist in the earth's surface, equal mass must underlie equal surface areas; in other words a great continental mass must be formed of lighter materials than that supposed to constitute the ocean floors and further in order to compensate for its greater heights these lighter continental material must extend downward to some distance under the continent and below the ocean floor level in order that unit areas beneath oceans and continents may remain in stable equilibrium.

The lithosphereic plate moves over asthenosphere which is onlyu possible when asthenospheric mantle behaves as an elasticviscous solid and the lithospheric mantle and crust behave as an elastic-plastic solid.

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