GLOSSARY

Abrasion Resistance: the ability of a material to withstand wear from its surface

Abrasive: any hard material used in the wearing, grinding or rubbing away by friction such as sandpaper, emery, garnet or the like.

Atmosphere: The envelope of gases surrounding the earth and held to it by friction. It has four layers:

• troposphere – from sea level to 8-16 kilometers (5-10 mi) above the earth

• stratosphere - up to 48 kilometers (30 miles)

• mesosphere – up to 96 kilometers (60 miles)

• thermosphere – up to 500 kilometers (300 miles) or more

Calcium Carbonate: One of the most abundant inorganic (nonliving) substances in nature. The white powder or colorless crystals are the major part of sedimentary rock, particularly in marble, limestone and chalk, as well as in animal shell and bones. They are used in antacids, tooth powders, white paints, cement and lime as well as other important chemical uses.

Cementation: The process where sediments are joined together into hard, compact rock. Common sedimentary cements are iron, silica and lime.

Chalk: A limestone or soft form of calcium carbonate made of marine shells. It is white or light colored, fine-grained, easily broken up and liquids easily go through it.

Cleavage: The splitting of a rock or mineral. Splitting in one place is one way cleavage, two places, two way cleavage and three places three way cleavage. Some rocks do not split cleanly but break into pieces with uneven surfaces.

Compaction: The process of pressing sediment together because of an increase in weight from deposits on top or by pressure from the Earth’s movements.

Compression: The changing of the Earth’s crust through folding and faulting by pressure from sediments above or by contraction (squeezing) stress.

Conglomerate: Sedimentary rock made up of pieces of rock or minerals in sand, silt or cementing material.

Crystallization: A metamorphic process where crystal mineral grains are made in rocks.

Deposition: The process where rock sediments, particles and other materials are laid down naturally in beds, veins or deposits.

Erosion: The loosening and wearing away of the Earth’s surface.

Extrusive: Any igneous material that has been ejected or poured out onto the Earth’s surface.

Glacial Till: Mixed material deposited by glacier ice and made up of clay, silt, sand, gravel and boulders.

Glacier: A large mass of land ice by the compacting (squeezing together) of snow. It flows slowly down slope under its own weight.

Grain Size: The size or range of sizes of grain particles or mineral grains in a sediment or rock.

Hardness: Minerals are rated 1-10 according to hardness on the Mohs’ Scale of hardness. 1 is very soft (talc) and 10 is very hard (diamond). Your fingernail is about 2.

Hydrochloric Acid: An acid with a strong odor that is highly corrosive (wears away), toxic and irritating.

Hydrosphere: The part of the Earth that is water, including liquid water, ice and water vapor on the surface, underground or in the atmosphere.

Igneous Rock: Rocks formed when hot magma in the Earth cools rapidly and becomes a solid. Magma forced out of the Earth’s surface makes extrusive igneous rocks (obsidian and pumice) while magma that fills in between layers of rocks and cools slowly is called intrusive igneous rocks (granite).

Intrusive: Molten, hot liquid material, forced into older rocks or between rock layers, which hardens before it reaches Earth’s surface.

Lower Mantle: The part of the Earth’s mantle 1,000 kilometers below the surface.

Lithosphere: The solid or land part of the Earth made up of the crust and upper mantle.

Magma: Liquid, hot rock (molten) material made inside the Earth’s surface which make up igneous rocks.

Mantle: The inside part of the Earth below the crust and above the core. It goes down to a depth of 3480 kilometers below the surface.

Mortar: A strong, bowl like vessel used to crush a substance into powder using a pestle.

Metamorphic Rock: Sedimentary or Igneous rocks that have been changed by heat, pressure or chemical action.

Minerals: Naturally occurring nonliving (inorganic) substances with a definite chemical makeup, crystal forms, and chemical and physical properties.

Plane: A flat or level surface.

Plutonic Rock: Medium to course grained intrusive igneous rock made by the hardening of magma.

Property: A quality that describes something or how something works.

Resistance: This works against (opposes) something like the flow of current.

Rock Cycle: The different stages Earth’s materials may go through when they go from one kind of a rock to another.

Rocks: Hard, solid parts of the Earth’s crust. Most are made up of a combination of minerals.

Sedimentary Rock: Rocks made up of parts of older rocks, which have been broken up and carried away, then deposited gradually, usually in layers.

Sediment: Pieces of rock or mineral that are carried by wind, water or ice, which end up in layers on the surface of the Earth.

Streak: The color of the powder making up rocks that we get by rubbing the rock or mineral across a piece of unglazed tile.

Texture: The way a rock looks or the way a rock or mineral is made up, such as the grain size or shape.

Tectonic Plate: One of several large, movable blocks of a continent or ocean crust that move as one piece.

Weathering: The natural breakdown of rocks and minerals by the air and other things like wind, rain and temperature changes.

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