Largest time unit in the geological time scale

Second largest time unit in the geologic time scale, defined by differences in life forms that are preserved in rocks

Third largest time unit in the geologic time scale, measured in tens of millions of years

Time unit in the geological time scale smaller than a period, measured in hundreds of thousands to millions of years

Is a system of categorizing living things

Is characterized by the formation of modern continents and the diversification of mammals and plants

Is characterized by the development of flying reptiles, birds, and flowering plants, and by the appearance and extinction of dinosaurs

Great explosion of life at the beginning of the era and ends with the largest mass extinction in the history of our planet

Informal unit of geologic time consisting of the first three eons during which Earth formed and became habitable

The remains or traces of an organism preserved from the geologic past

A fossil that is associated with a particular span of geological time

Establishing the order of past geologic events

Stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it

Method that enables scientists to determine the actual age of certain rocks and other objects

The branch of geology concerned with the order and relative position of strata and their relationship to the geological time scale

The theory that changes in the Earth’s crust during geological history have resulted from the action of continuous and uniform processes

States that layers of sediment are originally deposited horizontally under that action of gravity

Is a principle of geology that states that the geologic feature which cuts another is the younger of the two features

Is a relatively thin layer of sedimentary rock that is readily recognized on the basis of either its distinct physical characterizes or fossil content and can be mapped over a very large geographic area

Is a principle of geology that states that the geologic feature which cuts another is the younger of the two features