Explanation: The law of faunal succession, is based on the observation that sedimentary rock strata contain fossilized flora and fauna. These fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances. According to this law, the order for animals is as follows; animals with shells; fishes; amphibians; reptiles; mammals; birds; humans.
Natural gas was the largest source—about 40%—of U.S. electricity generation in 2020. Natural gas is used in steam turbines and gas turbines to generate electricity. Coal was the third-largest energy source for U.S. electricity generation
