What is the role of the greenhouse gases in the atmosphere? a) they trap some of the sun's heat energy within the atmosphere, to maintain earth's average temperature. b) they prevent most of the sun's rays from reaching earth, thereby preventing earth from heating up. c) they divert the sun's heat from the equator to the poles, causing the ice caps to melt, leading to global warming. d) they destroy the ozone layer, allowing harmful ultraviolet rays of the sun to reach the surface of earth.

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.