A(n) is a section of earth's crust and rigid upper mantle ridge island plate continent

What role did the waterways of europe play in development of europe's economy

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Where does the availability of water pose the greatest problem