Measuring Time and Earth's History

These flashcards cover key vocabulary terms from the lecture on measuring time and the history of Earth.

Absolute age

The actual age of a rock or fossil, determined through methods like radiometric dating.

Geologic time scale

A system of chronological dating that relates geological strata to time.

Eons

The largest divisions of geologic time, encompassing billions of years.

Stratigraphy

The study of rock layers and layering, used to understand the sequence of geological events.

Radiometric dating

A method for determining the age of an object by measuring the amount of radioactive isotopes present.

Index fossils

Fossils of organisms that were widespread but only existed for a short period of geologic time, used to identify and date the layers of rock.

Paleozoic era

A major era in Earth's history characterized by the emergence of fish, amphibians, and reptiles.

Mesozoic era

The era during which dinosaurs lived and thrived, along with the development of mammals and birds.

Cenozoic era

The current geological era, marked by the evolution of mammals and the rise of humans.

Incremental dating

Methods of dating that provide age estimates based on the accumulation of material, like tree rings.

Correlative dating

A dating method that compares and maps the ages of rocks and fossils from different locations.

Uniformitarianism

The principle that the processes affecting the Earth today have worked in the same way throughout its history.

Fossil record

The history of life as documented by fossils, providing insights into the types of organisms that existed at various times.

Trace fossils

Fossils that provide evidence of the activities of ancient organisms, such as tracks, burrows, or feces.

Faunal succession

The principle that different layers of rock contain different types of fossils, indicative of the periods they represent.

Half-life

The time required for half of a quantity of a radioactive isotope to decay, used for dating purposes.

Dendrochronology

The scientific method of dating tree rings to determine age and environmental conditions.

Mass extinction

A significant event in Earth's history when a large number of species died out in a relatively short period of time.