What two limitations do the wood-block analogies of Earth-scale isostasy have?
What will be an ideal response?
Answer: 1. The wood-block models assume a very weak crust that cannot resist deformation when any weight is place on top of it. The models also assume that faults penetrate completely through the crust so that adjacent blocks of crust readily slide up and down past one another while adjusting to changes in crustal thickness. In reality, the upper crust is strong, and the entire crust is not penetrated by faults because plastic flow occurs in the hot lower crust.
2. The mantle is almost entirely made up of solid rock, not liquid. Although the hot mantle flows like a very high viscosity fluid, this flow is much slower than the adjustment of water level to bobbing wood blocks. The crust can only move as quickly as the mantle very, very slowly flows from one place to another to equalize the pressure below regions of changing crustal weight.
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Draw or describe a scientific model using at least five steps.
What will be an ideal response?
The star nearest the Earth is
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Answer the following statement(s) true (T) or false (F)
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What will be an ideal response?