Historical geology or palaeogeology is a discipline that uses the principles and methods of

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

to reconstruct the

geological history of Earth Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

. Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, gradual and sudden, over this

deep time Deep time is a term introduced and applied by John McPhee to the concept of geologic time in his book ''Basin and Range'' (1981), parts of which originally appeared in the ''New Yorker'' magazine. The philosophical concept of geological time w ...

. It focuses on geological processes, such as

plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

, that have changed the Earth's surface and subsurface over time and the use of methods including

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...

structural geology Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover informatio ...

paleontology Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

, and

sedimentology Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation (erosion and weathering), transport, deposition and diagenesis. Sedimentologists apply their understanding of mo ...

to tell the sequence of these events. It also focuses on the

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

life Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energ ...

during different time periods in 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 geochrono ...

Historical development

During the 17th century,

Nicolas Steno Niels Steensen ( da, Niels Steensen; Latinized to ''Nicolaus Steno'' or ''Nicolaus Stenonius''; 1 January 1638 – 25 November 1686law of superposition The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the ...

, the

principle of original horizontality The principle of original horizontality states that layers of sediment are originally deposited horizontally under the action of gravity. It is a relative dating technique. The principle is important to the analysis of folded and tilted strata. ...

, and the

principle of lateral continuity The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or oth ...

. 18th-century geologist

James Hutton James Hutton (; 3 June O.S.172614 June 1726 New Style. – 26 March 1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist and physician. Often referred to as the father of modern geology, he played a key role i ...

contributed to an early understanding of the

Earth's history The 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 constant geologic ...

by proposing the theory of

uniformitarianism Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in ...

, which is now a basic principle in all branches of geology. Uniformitarianism describes an

formed by the same

natural phenomena Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are p ...

that are at work today, the product of slow and continuous geological changes. The theory can be summarized by the phrase "the present is the key to the past." Hutton also described the concept of deep time. The prevailing conceptualization of Earth history in 18th-century Europe, grounded in a literal interpretation of

Christian scripture A biblical canon is a set of texts (also called "books") which a particular Jewish or Christian religious community regards as part of the Bible. The English word ''canon'' comes from the Ancient Greek, Greek , meaning "ruler, rule" or "measu ...

, was that of a young Earth shaped by catastrophic events. Hutton, however, depicted a very old Earth, shaped by slow, continuous change.

Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...

further developed the theory of uniformitarianism in the 19th century. Modern geologists have generally acknowledged that Earth's geological history is a product of both sudden, cataclysmic events (such as meteorite impacts and

volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

) and gradual processes (such as weathering, erosion, and deposition). The discovery of

radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

in the late 19th century and the development of

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

techniques in the 20th century provided a means of deriving

absolute Absolute may refer to: Companies * Absolute Entertainment, a video game publisher * Absolute Radio, (formerly Virgin Radio), independent national radio station in the UK * Absolute Software Corporation, specializes in security and data risk manage ...

ages of events in geological history.

Use and importance

Geology is considered a historical science; accordingly, historical geology plays a prominent role in the field. Historical geology covers much of the same subject matter as physical geology, the study of geological processes and the ways in which they shape the Earth's structure and composition. Historical geology extends physical geology into the past. Economic geology, the search for and extraction of

fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...

and

raw materials A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feedst ...

, is heavily dependent on an understanding of the geological history of an area. Environmental geology, which examines the impacts of

natural hazard A natural hazard is a natural phenomenon that might have a negative effect on humans and other animals, or the environment. Natural hazard events can be classified into two broad categories: geophysical and biological. An example of the distinct ...

s such as

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

s and

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...

, must rely on a detailed knowledge of geological history.

Methods

Stratigraphy

Layers of rock, or

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

, represent a

geologic record The geologic record in stratigraphy, paleontology and other natural sciences refers to the entirety of the layers of rock strata. That is, deposits laid down by volcanism or by deposition of sediment derived from weathering detritus (clays, sand ...

of Earth's history. Stratigraphy is the study of strata: their order, position, and age.

Structural geology

Structural geology is concerned with rocks' deformational histories.

Paleontology

Fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

are organic traces of Earth's history. In a historical geology context, paleontological methods can be used to study fossils and their environments, including surrounding rocks, and place them within the geologic time scale.

Sedimentology

Sedimentology is the study of the formation, transport, deposition, and diagenesis of

sediments Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...

Sedimentary rocks Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles t ...

, including limestone, sandstone, and shale, serve as a record of Earth's history: they contain fossils and are transformed by geological processes, such as weathering, erosion, and deposition, through deep time.

Relative dating

Historical geology makes use of relative dating in order to establish the sequence of geological events in relation to each another, without determining their specific numerical ages or ranges.

Absolute dating

Absolute dating allows geologists to determine a more precise chronology of geological events, based on numerical ages or ranges. Absolute dating includes the use of

methods, such as

radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...

, potassium–argon dating, and

uranium–lead dating Uranium–lead dating, abbreviated U–Pb dating, is one of the oldest and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routi ...

Luminescence dating Luminescence dating refers to a group of methods of determining how long ago mineral grains were last exposed to sunlight or sufficient heating. It is useful to geologists and archaeologists who want to know when such an event occurred. It uses var ...

dendrochronology Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the study of climate and atmos ...

, and

amino acid dating Amino acid dating is a Dating methodology (archaeology), dating technique used to estimate the age of a specimen in paleobiology, molecular paleontology, archaeology, forensic science, taphonomy, sedimentary geology and other fields. This techniqu ...

are other methods of absolute dating.

Plate tectonics

The theory of plate tectonics explains how the movement of

lithospheric A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or ...

plates has structured the Earth throughout its geological history.Levin, Harold L.; King, David T. (2017). ''The Earth Through Time'' (11th ed.). Hoboken, New Jersey: John Wiley & Sons. p. 9. .

Weathering, erosion, and deposition

Weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

, and deposition are examples of gradual geological processes, taking place over large sections of the geologic time scale. In the

rock cycle The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Each rock type is altered when it is forced out of its equilibrium conditio ...

, rocks are continually broken down, transported, and deposited, cycling through three main rock types:

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

, and

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

Paleoclimatology

Paleoclimatology is the study of past climates recorded in geological time.

Brief geological history

External links

Geology - Earth history
, Encyclopedia Britannica
Historical Geology
, OpenGeology.org

, Lecture notes for course at the University of Maryland

Notes

{{DEFAULTSORT:Historical Geology