Coal and Petroleum

Fill in the blanks and complete the story.
About 300 million years ago the earth had dense ________ in low
lying wetland areas. Due to natural processes, like ______, these
forests got burried under the ________. As more ________ deposited
over them, they were compressed. The ________ also rose as they
sank deeper and deeper. Under high ________ and high ________,
dead plants got slowly converted into coal.