Discuss how a coal seam might be used as a key bed.

Coal seams refers to those distinctive thin beds of coal that are found to be existed in between two sedimentary rock layers. It is easily distinguishable because of its characteristic color such as dark brownish or blackish in color.

Coal is obtained from the dead remains of plants and trees that were buried millions of years ago, due to action of extreme pressure and temperature conditions. The process by which these vegetative matters are converted into coal is known as the carbonization.

This coal has extensive use such as the generation of electricity as well as in the production of steel and are obtained by two methods, such as the open cast mining and underground mining.

when it's short and dry.

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).