The Appalachian Mountains were formed about 500-400 million years ago. What has caused them to change so much over time

There are many factors that go into the changes made to the Appalachian Mts.; you've got wind erosion, water erosion from rain/snow melting, and tectonic plate movements that can either cause the mountains to grow or to shrink.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

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