Vocab

Fossil Remains, imprints, or traces of prehistoric organisms

Permineralized Remains Fossils in which the spaces inside are filled with minerals from groundwater

Carbon film A thin film of carbon residue that forms a silhouette of the original organism

Mold A cavity in a rock left behind from a decaying organism

Cast A copy of the original object formed by mineral-rich water or other sediment

Index fossil Remains of species that existed on Earth for relatively short periods of time, were abundant, and were widespread geographically.

Principle of Superposition The oldest rocks are on the bottom and the rocks become progressively younger toward the top

Relative age An objects age in comparison to the ages of other things

Unconformities A gap in a rock sequence

Absolute age The age, in years, of a rock or other object

Radioactive decay The process of breaking down

Half-life The time it takes for half of the atoms in the isotope to decay

Radiometric dating Calculating the absolute age of a rock by measuring the ratio of parent isotope to daughter product in a mineral and by knowing the half-life of the parent

Uniformitarianism Principle that states that Earth’s processes occurring today are similar to those that occurred in the past

Weathering The breaking down or disintegration of substances such as rocks and minerals by physical, chemical, or biological changes

Erosion The movement of sediment or soil from one location to another by means of water, wind, or ice

Deposition When particles carried by water, ice, or wind are deposited in another location

Metamorphic rock Rocky material experiences intense heat and pressure in the crust of the earth.

Igneous rock Formed when magma cools and makes crystals.

Sedimentary rock Form at or near the earth's surface at relatively low temperatures and pressures primarily by: deposition by water, wind or ice