a flat landform that rises steeply above the surrounding land; smaller than a plateau
a flat-topped hill, smaller than a mesa
a deep narrow valley with steep sides
how water, wind, or ice slowly carry away soil and rock
when a kind of animal or plant slowly changes over many years to survive in its environment
an area of the Great Plains that experienced terrible droughts and dust storms
underground layers of rock or gravel that trap water causing people to dig wells to bring this water to the surface
a way to grow crops with only rain water
a high, flat landform that rises steeply above the surrounding land
a nonrenewable natural resource also called oil formed underground over millions of years from the remains of dead plants also called "black gold."
oil that bubbles up from the ground and has not been refined
a factory where crude oil is refined, or separated into parts to be used
chemicals made from petroleum produced in refineries
countries buying and selling goods to each other
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