The great majority of asphalt used commercially is obtained from petroleum. Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of asphalt/bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as asphalt/bitumen, kerogen, or petroleum. COUNT 5
QSN1 From where does most asphalt come? ANS1 petroleum QSN2 What are the sources of natural deposits of asphalt? ANS2 once-living things QSN3 How much heat is required for the natural production of asphalt? ANS3 above 50 °C QSN4 Besides heat, what other requirement is needed to form asphalt? ANS4 pressure QSN5 What other product of heat and pressure does the formation of asphalt and petroleum  produce? ANS5 kerogen