6. Exercises VI

Petroleum is formed by burying aquatic plants and rocksplants and sandplants and woodsplants and animals below the sea bed. The marine animals and plants died thousands of years ago and settled down in the bottom of the sea. In anaerobic conditions, microorganisms decompose this coal mattersolid matterorganic matterinorganic matter. Due to low pressurehigh pressurehigh tempraturelow temprature and heat, the dead remains of tiny plants and animals were slowly converted into petroleum.