As it cools it becomes a very hard type of igneous rock. This one first formed over 350 million years ago. Then, millions of years after that, during the last ice age - when the land was covered ...

It features scenes of farmers tilling soil, majestic mountain roads, sedimentary rock formations, and granite and marble quarries. The film also highlights natural phenomena such as volcanic ...

background information on the structure and forces affecting the Earth in relation to rock formation a more practical hand-specimen guide with examples of rock samples commonly found in the United ...