the appalachian mountains may have once been as lofty as the himalayan-tibetan mountain belt is today. why are they not this high now? group of answer choices they formed long ago, and erosion has beveled them to their present low elevation. they developed a dense crustal root following collision, and isostasy forced them to sink to their present elevation. the mountains cooled following the collision, which increased the density of the rocks by cooling, then isostasy forced the mountains to sink.
