Said of a clastic sedimentary rock composed of a single mineral species.

A mass or body of rock particles, mineral grains, or both. Any of several hard, inert materials, such as sand, gravel, slag, or crushed stone, used for mixing with a cemeting or bituminous material to [..]

Photosynthetic, almost exclusively aquatic plants of a large and diverse group, including seaweeds and their fresh-water allies. They range in size from simple unicelluar forms to giant kelps several [..]

An outspread, gently sloping mass of alluvium deposited by a stream in an arid or semi-arid region where a stream issues from a narrow canyon onto a plain or valley floor.

A rain of airborne volcanic ash falling from an eruption cloud.

One of the many small celestial bodies in orbit around the sun. Most asteroid orbits are between those of planets Mars and Jupiter.

A dark colored igneous rock, commonly extrusive, composed primarily of calcic plagioclase and pyroxene; the fine-grained equivalent of gabbro.

The solid rock that underlies gravel, soil, or other surficial material.

A mound-like or circumscribed mass of rock built by sedentary organisms such as corals, stromatoporoids, or algae, and enclosed in rock of different lithological character.

A coarse-grained clastic rock, composed of angular broken rock fragments held together by a mineral cement or a fine-grained matrix.