However, it is believed by some scientists that when the weight of one of the polar ice caps becomes imbalanced and greater than that of the other polar ice cap, the entire crust of the earth will rapidly shift. These rapid shifts can dramatically change the climate on a continent. This may be why woolly mammoth bones and bodies, animals who could only live in a warm climate, are found in Siberia. As the earth cools, it cracks into plates. Mountains are formed by subduction.
Subduction occurs when two plates come together, pushing the land upward.
This is why the fossils of sea creatures are always found in mountains. This is also the reason for earthquakes. When two plates slide by each other, they create friction. As the movement overcomes the friction, the earth moves rapidly producing an earthquake. Life began on Earth about 3.5 billion years ago.