"It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history."
An introduction to geologic time and the history of Earth, including the formation of continents, the evolution of life, and the major events in geological history.
Fossils: The remains or traces of plants and animals that lived in the past, used as geological age markers and to understand past life forms.
Radioactive decay: The process by which unstable isotopes release energy and transform into more stable forms, used to determine the absolute age of rocks and minerals.
Stratigraphy: The study of layers of sedimentary rock and their formation over time, used to reconstruct the history of the Earth's surface.
Plate tectonics: The theory that the Earth's crust is divided into plates that move and shift over time, causing geological changes such as earthquakes and mountain formation.
Geological time scale: The system of dividing Earth's history into chronological periods and eras based on major geological and biological events.
Geological features: The physical characteristics of the Earth's surface, such as mountains, valleys, and canyons, which are shaped by geological processes over millions of years.
Paleomagnetism: The study of the Earth's magnetic field and its effect on rocks, used to reconstruct the movement of the Earth's plates over time.
Geological dating methods: A variety of techniques used to determine the age of rocks and fossils, including radiometric dating, tree-ring dating, and thermoluminescence dating.
Climate and geologic time: The relationship between the Earth's climate and geological processes over time, including the impact of climate change on geological features.
Evolution and geologic time: The study of the evolution of life on Earth and the relationship between major geological events and the development of different species.
Eons: The largest subdivision of geological time, encompassing billions of years. The history of Earth is divided into four eons: Hadean, Archean, Proterozoic, and Phanerozoic.
Eras: Subdivided into periods, eras are distinguished by the evolution of life and the major geological events of the time. There are three eras: Paleozoic, Mesozoic, and Cenozoic.
Periods: Subdivisions of eras based on rock layers and fossils. Each period has a distinct set of rocks, fossils, and geologic events that define it.
Epochs: A subdivision of a geologic period, marked by distinctive rock layers and fossils.
Ages: The smallest subdivision of geologic time, often measured in tens of thousands or hundreds of thousands of years.
Pre-Cambrian time: The period of Earth's history before the Cambrian era, spanning roughly 4.6 billion to 541 million years ago.
Hadean time: The earliest period of Earth's history, lasting from the formation of the Earth around 4.6 billion years ago to the start of the Archean eon around 4 billion years ago.
Archean time: A period of Earth's history from 4 billion to 2.5 billion years ago, characterized by the formation of stable continents.
Proterozoic time: A period of Earth's history from 2.5 billion to 541 million years ago, characterized by the emergence of life and the formation of oxygen in the atmosphere.
Phanerozoic time: The current eon of Earth's history, spanning from 541 million years ago to the present day.
Paleozoic era: A period of Earth's history from 541 million to 252 million years ago, characterized by the emergence and diversification of complex life forms.
Mesozoic era: A period of Earth's history from 252 million to 66 million years ago, marked by the rise and fall of dinosaurs and the evolution of early mammals.
Cenozoic era: A period of Earth's history from 66 million years ago to the present day, characterized by the evolution of modern mammals and the rise of Homo sapiens.
Quaternary period: The most recent period of the Cenozoic era, spanning from 2.6 million to the present day and marked by the emergence of Homo sapiens and the start of the Ice Age.
"...uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks)."
"The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils."
"The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS)."
"Their primary objective is to precisely define global chronostratigraphic units of the International Chronostratigraphic Chart (ICC) that are used to define divisions of geologic time."
"While some regional terms are still in use, the table of geologic time presented in this article conforms to the nomenclature, ages, and color codes set forth by the ICS."
"The chronostratigraphic divisions are in turn used to define geochronologic units."
"It is a system of chronological dating that uses the rock record of Earth."
"Earth scientists, including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists."
"Identifying features such as lithologies, paleomagnetic properties, and fossils."
"The International Commission on Stratigraphy is a constituent body of the International Union of Geological Sciences."
"To determine the age of rocks."
"It is used to define divisions of geologic time."
"Geology, paleontology, geophysics, geochemistry, and paleoclimatology."
"The timing and relationships of events in geologic history."
"The process of relating strata to time."
"The International Commission on Stratigraphy."
"Using the International Chronostratigraphic Chart."
"Through the scientific branch of geology that aims to determine the age of rocks."
"The rock record of Earth is the basis for the geologic time scale."