question archive There are a number of sostatic models used to explain different areas of the Earth
There are a number of sostatic models used to explain different areas of the Earth
Subject:Earth SciencePrice: Bought3
There are a number of sostatic models used to explain different areas of the Earth. We will explore two of them. The Alry model (named after George Biddell Airy, British astronomer and mathematician who also was responsible for establishing Greenwich, England as the prime meridian) attempts to explain differences in elevation through variations in crustal thickness. In contrast, the Pratt model (named after another British astronomer and mathematician named John Henry Pratt who worked in India on geographic surveys) seeks to explain differences in elevation through lateral differences in rock density. The difference between the two models Is shown in Figure S. But why are there separate models? Well, blame plate tectonics or at least a heterogeneous Earth. The two models work better in different settings. In some plate tectonic settings, It really is the thickness of the lithos phone that matters as all of the lithosphere present is capped by the same type of crust, oceanic or continental. But in other areas, the crust that comprises the uppermost part of the lithosphere varies laterally from rock of one density to rock of another. And in some settings, things can get even more complicated and neither of these two models is a good match, so we have to use elements of both or abandon them entirely in favor of yet another isostacy model. A B dense asthenosphere Figure 5. Two models of isostacy. In A, the Airy model, differences in elevation are due to lateral differences in the thickness of the lithosphere overlying a dense heat softened asthenosphere that can flow. In B, the Pratt model, differences in elevation are due to lateral differences in the density of the lithosphere, with density of each block increasing from light to dark colors. At oceanic hotspots, basaltic magma rises through basaltic crust to build large volcanoes on the seafloor that can rise above sea level to form islands. Question B (1 point) Which isostacy model would be the best fit for an oceanic hots pot? - Airy model . Pratt model - neither of the two would really fit
