The supercontinent which formed at the end of the Paleozoic Era and began breaking up about 200 million years ago to form today's continents. . A radioactive isotope that changes to a different, daughter isotope when its nucleus decays. The preexisting rock from which a metamorphic rock forms. A tectonically inactive continental margin characterized by a lack of earthquakes and volcanic activity. A bare rock surface that provides a protective rock cover over the material beneath it.
Pebbles are the smallest type of gravel. .
Usually forms from molten rock rich in water or other volatiles that facilitate the growth of large crystals. Forms sills and dikes . Mudstone, shale, siltstone, and claystone are all pelitic . A stream that runs continuously throughout the year. The ability of a rock or other material to allow water to flow through its interconnected spaces.