Now we'll consider Pratt isostasy. Assuming this compensation model, what would the average density of the Appalachians be if their average elevation is 2.9 km higher than adjacent cratonic regions which are composed of rock of density 2700 kg/m3? Assume a mantle density of 3300 kg/m3 and thickness of cratonic crust of 42 km. Provide your answer in kg/m3 to the nearest whole number. Think about the answer here: is this true of the Appalachians that their density is less than, greater than, or equal to the surrounding (cratonic) crustal density rock. Think about what this means for Pratt vs. Airy isostasy