The leading causes of u. s. deaths in middle age are and

according to hess's theory, when the magma cooled, it would expand and push the tectonic plates apart. it would push the north and south america plates to the west and eurasia and africa ones to the east. the atlantic ocean would get wider but the coastlines of the masses would stay the same.

harry hammond hess was a geologist and a united states navy officer in the second world war. he is considered to be one of the founding fathers of the theory of plate tectonics. he is known for his theories on sea floor spreading, stating that the movement of the continents was the result of see floor spreading. the continents are attached to the plates and do not move separately. the plates themselves shift and change shape, carrying the continents along.