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geologic time, the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins at the start of the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day.
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).
Humans subdivide time into useable units such as our calendar year, months, weeks, and days; geologists also subdivide time. They have created a tool for measuring geologic time, breaking it into useable, understandable segments. For the purposes of geology, the “calendar” is the geologic time scale.
Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years (Harland and others, 1982).
The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history. Eon. Era. Period. Epoch. Biology. Geology. Years Ago. Duration.
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy).
The BGS geological timechart provides colourful reference material for use in schools, colleges and at home, setting out the geological timescale and geochronological terms we use at BGS. You can browse the timechart by geological era in the page below or download the Phanerozoic Timechart as a pdf.
Understanding the divisions of time in the Geologic Time Scale is crucial for comprehending the history of our planet and the evolution of life on Earth. The Geologic Time Scale is divided into several large units of time, including eons, eras, periods, and epochs.
Geologic time scale with a linear time axis. This time scale is available as a printable .pdf document. You can download this printable time scale and make copies for personal use. Geologists have divided Earth's history into a series of time intervals. These time intervals are not equal in length like the hours in a day.
Currently, the Anthropocene has an informal designation, with a proposed age span extending from the present to a beginning point between ca. 15,000 yr B.P. and as recent as 1960 CE. The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon.
At GSA you'll find the resources, confidence, and connections you need to reach fulfilling new heights in your geoscience career.
The geologic time scale is a system used by scientists to describe Earth's history in terms of major geological or paleontological events (such as the formation of a new rock layer or the appearance or demise of certain lifeforms). Geologic time spans are divided into units and subunits, the largest of which are eons.
Here is a brief look at the four periods of the Geologic Time Scale that track the Earth's history: Precambrian, Paleozoic, Mesozoic, and Cenozoic.
Scientists have put together the geologic time scale to describe the order and duration of major events on Earth for the last 4 1 ⁄ 2 billion years.
By examining the composition of rocks and the types of fossils in them, scientists have created a timeline of Earth’s history. It is broken up into sections based on major events, like global climate changes and mass extinctions. Use this infographic to explore the evolution of Earth and the life upon it.
Each eon, era, period, and epoch is defined by major geological or paleontological events. The eons are the Hadean, Archean, Proterozoic, and Phanerozoic. The Phanerozoic Eon is the eon of visible life, and is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
Numerical age estimates and picks of boundaries usually follow the Cohen et al. (2013, updated) compilation. The numbered epochs and ages of the Cambrian are provisional. A “~” before a numerical age estimate typically indicates an associated error of ±0.4 to over 1.6 Ma.
Geologists start counting “geologic time” from Earth’s surface downward; that is, starting with younger surficial deposits and descending into older rocks and deeper time. Geologists count back more than 4 billion years to the oldest Earth materials.
In this Earth timeline, we lay out all the pieces on the floor. What sequence of events has unfolded for Earth to support life and for it to evolve? The Big Bang created all matter in the universe. This includes the sun, planets, and our solar system. At the center, the sun swept in smaller elements like hydrogen and helium.
geologic history of Earth, evolution of the continents, oceans, atmosphere, and biosphere. The layers of rock at Earth ’s surface contain evidence of the evolutionary processes undergone by these components of the terrestrial environment during the times at which each layer was formed.