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A geological event is a temporary and spatially 
Geological events range in time span by orders of magnitude, from seconds to millions of years, and in spatial scale from local to regional and, ultimately, global. In contrast to chronostratigraphic or geochronological units, that define the boundaries between periods,
heterogeneous
Homogeneity and heterogeneity are concepts relating to the uniformity of a substance, process or image. A homogeneous feature is uniform in composition or character (i.e., color, shape, size, weight, height, distribution, texture, language, i ...
and dynamic (diachronous
In geology, a diachronism ( Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where it was deposite ...
) happening in Earth history
The natural history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by consta ...
that contributes to the transformation of Earth system and the formation of geological strata. Event stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithost ...
was first proposed as a system for the recognition, study and correlation of the effects of important physical or biological events on the broader stratigraphical record.
Geological events range in time span by orders of magnitude, from seconds to millions of years, and in spatial scale from local to regional and, ultimately, global. In contrast to chronostratigraphic or geochronological units, that define the boundaries between periods, epoch
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided b ...
s and other units of the geologic time scale
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 geochro ...
, complex dynamic diachronous
In geology, a diachronism ( Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where it was deposite ...
changes are inherent to the event-stratigraphy paradigm. The lithostratigraphic
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology.
In general, strata are primarily igneous ...
or biostratigraphic
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ...
boundaries that mark the onset and termination of geological events in the stratigraphic record may be diachronous
In geology, a diachronism ( Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where it was deposite ...
, whereas those of formal chronostratigraphic or geochronologic units have basal boundaries that are isochronous
A sequence of events is isochronous if the events occur regularly, or at equal time intervals. The term ''isochronous'' is used in several technical contexts, but usually refers to the primary subject maintaining a constant period or interval ( ...
.
Examples of geological events include a single footprint, an earthquake
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...
, a series of volcanic eruptions
A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior h ...
, the formation of mountains (orogenies
Orogeny () is a mountain-building process that takes place at a convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involv ...
), the Great Oxidation Event
The Great Oxidation Event (GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, was a time interval during the Earth's Paleoproterozoic era when the Earth's atmosphere an ...
(GOE) of 2.4-2.0 billion years ago and the Great Ordovician Biodiversification Event
The Great Ordovician Biodiversification Event (GOBE) was an evolutionary radiation of animal life throughout the Ordovician period, 40 million years after the Cambrian explosion, whereby the distinctive Cambrian fauna fizzled out to be replaced wi ...
(GOBE) ~500 Ma. The event paradigm is firmly embedded in Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
science, as the subdivision of quaternary time is based on the recognition of a succession of climatic events, principally glacial
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
and interglacial
An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...
cycles but also stadial
Stadials and interstadials are phases dividing the Quaternary period, or the last 2.6 million years. Stadials are periods of colder climate, and interstadials are periods of warmer climate.
Each Quaternary climate phase has been assigned with a ...
s and interstadial
Stadials and interstadials are phases dividing the Quaternary period, or the last 2.6 million years. Stadials are periods of colder climate, and interstadials are periods of warmer climate.
Each Quaternary climate phase has been assigned with a ...
s. Highly resolved stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithost ...
sequences, such as those from ice core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...
s, provide evidence of much shorter-term millennial-scale climatic events that are superimposed on these broad glacial cycle
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and gr ...
s. Other short-term happenings, such as Dansgaard–Oeschger event
A Dansgaard–Oeschger event (often abbreviated D–O event), is a rapid climate fluctuation; such events occurred 25 times during the last glacial period. Some scientists say that the events occur quasi-periodically with a recurrence time being ...
s and Heinrich event
A Heinrich event is a natural phenomenon in which large groups of icebergs break off from the Laurentide ice sheet and traverse the Hudson Strait into the North Atlantic. First described by the marine geologist Hartmut Heinrich, they occurred dur ...
s, are evident in ice-core sequences and deep-ocean sediment records, respectively. Some scientists have proposed that the Anthropocene
''Anthropocene'' is a term that has been used to refer to the period of time during which human impact on the environment, humanity has become a planetary force of change. It appears in scientific and social discourse, especially with respect to ...
is more consistent with the concept of a geological event than with a formal chronostratigraphic/geochronological unit, such as an epoch
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided b ...
of geologic time
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 geochronolo ...
.
References
{{reflist Geology terminology Events in the geological history of Earth