Geologic time scale

This time scale is available as a printable. You can download this printable time scale and make copies for personal use.

Geologic time scale

Early history[ edit ] In Ancient GreeceAristotle BCE observed that fossils of seashells in rocks resembled those found on beaches — he inferred that the fossils in rocks were formed by living animals, and he reasoned that the positions of land and sea had changed over long periods of time.

Leonardo da Vinci — concurred with Aristotle's interpretation that fossils represented the remains of ancient life. Steno argued that rock layers or strata were laid down in succession, and that each represents a "slice" of time.

Geologic time | Periods, Time scale, & Facts | caninariojana.com

He also formulated the law of superposition, which states that any given stratum is probably older than those above it and younger than those below it. While Steno's principles were simple, applying them proved challenging. Steno's ideas also lead to other important concepts geologists use today, such as relative dating.

Over the course of the 18th century geologists realized that: Sequences of strata often become eroded, distorted, tilted, or even inverted after deposition Strata laid down at the same time in different areas could have entirely different appearances The strata of any given area represented only part of Earth's long history The Neptunist theories popular at this time expounded by Abraham Werner — in the late 18th century proposed that all rocks had precipitated out of a single enormous flood.

John McPhee asserts that "as things appear from the perspective of the 20th century, James Hutton in those readings became the founder of modern geology". This theory, known as " Plutonism ", stood in contrast to the "Neptunist" flood-oriented theory. Formulation of geologic time scale[ edit ] The first serious attempts to formulate a geologic time scale that could be applied anywhere on Earth were made in the late 18th century.

The most influential of those early attempts championed by Werneramong others divided the rocks of Earth's crust into four types: Primary, Secondary, Tertiary, and Quaternary.

Keep Exploring Britannica

Each type of rock, according to the theory, formed during a specific period in Earth history. It was thus possible to speak of a "Tertiary Period" as well as of "Tertiary Rocks.

Geologic time scale

The identification of strata by the fossils they contained, pioneered by William SmithGeorges CuvierJean d'Omalius d'Halloyand Alexandre Brongniart in the early 19th century, enabled geologists to divide Earth history more precisely. It also enabled them to correlate strata across national or even continental boundaries.

Geologic time scale. Take a journey back through the history of the Earth — jump to a specific time period using the time scale below and examine ancient life, climates, and geography. © The Geological Society of America, Inc. The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to caninariojana.com is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history.

If two strata however distant in space or different in composition contained the same fossils, chances were good that they had been laid down at the same time. Detailed studies between and of the strata and fossils of Europe produced the sequence of geologic periods still used today.

Geologic time scale

Naming of geologic periods, eras and epochs[ edit ] Early work on developing the geologic time scale was dominated by British geologists, and the names of the geologic periods reflect that dominance.

The "Cambrian", the classical name for Wales and the "Ordovician", and "Silurian", named after ancient Welsh tribes, were periods defined using stratigraphic sequences from Wales. The "Permian" was named after PermRussia, because it was defined using strata in that region by Scottish geologist Roderick Murchison.The geologic time scale is an essential tool for understanding the history of Earth and the evolution of life.

In this lesson, explore the. Geologic time scale.

ADDITIONAL MEDIA

Take a journey back through the history of the Earth — jump to a specific time period using the time scale below and examine ancient life, climates, and geography. Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, , Geologic Time Scale v. Geological Society of America, caninariojana.com The geologic time scale is an essential tool for understanding the history of Earth and the evolution of life.

In this lesson, explore the principal eons, eras, periods, and epochs that help us. The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, periods, epochs, and ages.

© The Geological Society of America, Inc.

Geologic Time Scale - Geology (U.S. National Park Service)