Glossary of Terms



Basalt a fine-grained, dark-colored igneous rock.

Bedrock rock, sometimes exposed, but usually found under soil sediment.

Beds layers of sedimentary rock.

Conglomerate sedimentary rock made of rounded pebbles cemented together by a mineral substance (matrix) .

Erosion processes (running water, ice and wind) which loosen and remove rock from the earth’s surface.

Glacial Erratic a rock fragment different from the rock on which it lies, having been transported by a glacier.

Glacier a thick mass of ice, formed by compacted snow, with motion in a definite direction.

Hematite a red-colored iron ore.

Igneous rock formed by the cooling of molten material.

Impermeable having a structure that does not permit water to move through it.

Jurassic the second of three geologic periods in the Mesozoic era (180 - 135 million years ago).

Lava molten igneous rock that flows out and cools on the surface of the Earth.

Lithify to form rock by cementing or compressing sediments.

Matrix mineral material by which rock fragments are cemented.

Metamorphic rocks that in some way have been changed by temperature and pressure.

Mesozoic a span of geologic time from approximately 225 million years ago to 71 million years ago, and divided into smaller units called Triassic, Jurassic and Cretaceous.

Oxidation a chemical reaction combining with oxygen.

Pangaea supercontinent that broke apart in early Mesozoic time, forming separate continents and the Atlantic Ocean.

Puddingstone a conglomerate of round pebbles that contrast sharply with the finer-grained cement around them.

Quarry an open cliff face where rocks are removed to be used for building -stone, paving, etc.

Quartzite a metamorphosed form of sandstone.

Sandstone sedimentary rock composed of sand-sized minerals or rock grains.

Sedimentary rocks formed from fragments of other rocks, compressed or cemented together.

Shale sedimentary rock composed of mud that is a mix of clay materials and other fine textured mineral fragments.

Soil Creep slow movement of rock fragments down a gentle slope.

Spring a small pond or stream of water flowing naturally from the earth.

Trap Rock Scandinavian for "stairs," a construction term for basalt.

Triassic earliest of three Geologic periods in Mesozoic era (225 - 180 million years ago).