Historical geology
Encyclopedia
Historical geology is the use of the principles of geology
to reconstruct and understand the history of the Earth
. It focuses on geologic processes that change the Earth
's surface and subsurface; and the use of stratigraphy
, structural geology
and paleontology
to tell the sequence of these events. It also focuses on the evolution
of plant
s and animal
s during different time periods in the geological timescale. The discovery of radioactivity and the development of a variety of radiometric dating
techniques in the first half of the 20th century provided a means of deriving absolute versus relative ages of geologic history.
Economic geology
, the search for and extraction of energy
and raw materials, is heavily dependent on an understanding of the geological history of an area. Environmental geology
, including most importantly the geologic hazards of earthquake
s and volcanism
, must also include a detailed knowledge of geologic history.
s. The other, more famous, observations are often grouped together to form the laws of stratigraphy
.
James Hutton
and Charles Lyell
also contributed to early understanding of the Earth's history
with their observations at Edinburgh
in Scotland
concerning angular unconformity in a rock face and it was in fact Lyell that influenced Charles Darwin
greatly in his theory of evolution by speculating that the present is the key to the past. Hutton first proposed the theory of uniformitarianism
, which is now a basic principle in all branches of geology. Hutton also supported the idea that the Earth was very old
as opposed to prevailing concept of the time which said the Earth had only been around a few millennia. Uniformitarianism describes an Earth
created by the same natural phenomenon
that are at work today.
The prevailing concept of the 18th century in the West was that of a very short Earth history dominated by catastrophic
events. This view was strongly supported by adherents of Abrahamic religions based on a largely literal interpretation of their religious scriptural passages. The concept of uniformitarianism met with considerable resistance and the catastrophism vs. gradualism debate of the 19th century resulted. A variety of discoveries in the 20th century provided ample evidence that Earth history is a product of both gradual incremental processes and sudden cataclysmic events. Violent events such as meteorite impacts
and large volcanic explosions do shape the Earth's surface along with gradual processes such as weathering
, erosion
and deposition
much as they have throughout Earth history. The present is the key to the past - includes catastrophic as well as gradual processes.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
to reconstruct and understand the history of the Earth
Geological history of Earth
The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers...
. It focuses on geologic processes that change the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's surface and subsurface; and the use of stratigraphy
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
, structural geology
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 information about the history of deformation in the rocks, and...
and paleontology
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
to tell the sequence of these events. It also focuses on the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s and animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s during different time periods in the geological timescale. The discovery of radioactivity and the development of a variety of radiometric dating
Radiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
techniques in the first half of the 20th century provided a means of deriving absolute versus relative ages of geologic history.
Economic geology
Economic geology
Economic geology is concerned with earth materials that can be used for economic and/or industrial purposes. These materials include precious and base metals, nonmetallic minerals, construction-grade stone, petroleum minerals, coal, and water. The term commonly refers to metallic mineral deposits...
, the search for and extraction of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
and raw materials, is heavily dependent on an understanding of the geological history of an area. Environmental geology
Environmental geology
Environmental geology, like hydrogeology, is an applied science concerned with the practical application of the principles of geology in the solving of environmental problems. It is a multidisciplinary field that is closely related to engineering geology and, to a lesser extent, to environmental...
, including most importantly the geologic hazards of earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s and volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....
, must also include a detailed knowledge of geologic history.
Historical development
Nicolaus Steno, also known as Niels Stensen, was the first to observe and propose some of the basic concepts of historical geology. One of these concept was that fossils originally came from living organismOrganism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s. The other, more famous, observations are often grouped together to form the laws of stratigraphy
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
.
James Hutton
James Hutton
James Hutton was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. He is considered the father of modern geology...
and Charles Lyell
Charles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
also contributed to early understanding of the Earth's history
History of Earth
The history of the Earth describes the most important events and fundamental stages in the development of the planet Earth from its formation 4.578 billion years ago to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's...
with their observations at Edinburgh
Edinburgh
Edinburgh is the capital city of Scotland, the second largest city in Scotland, and the eighth most populous in the United Kingdom. The City of Edinburgh Council governs one of Scotland's 32 local government council areas. The council area includes urban Edinburgh and a rural area...
in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
concerning angular unconformity in a rock face and it was in fact Lyell that influenced Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
greatly in his theory of evolution by speculating that the present is the key to the past. Hutton first proposed the theory of uniformitarianism
Uniformitarianism (science)
In the philosophy of naturalism, the uniformitarianism assumption is that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic concept that "the present is the...
, which is now a basic principle in all branches of geology. Hutton also supported the idea that the Earth was very old
Age of the Earth
The age of the Earth is 4.54 billion years This age is based on evidence from radiometric age dating of meteorite material and is consistent with the ages of the oldest-known terrestrial and lunar samples...
as opposed to prevailing concept of the time which said the Earth had only been around a few millennia. Uniformitarianism describes an Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
created by the same natural phenomenon
Natural phenomenon
A natural phenomenon is a non-artificial event in the physical sense, and therefore not produced by humans, although it may affect humans . Common examples of natural phenomena include volcanic eruptions, weather, decay, gravity and erosion...
that are at work today.
The prevailing concept of the 18th century in the West was that of a very short Earth history dominated by catastrophic
Catastrophism
Catastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope. The dominant paradigm of modern geology is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
events. This view was strongly supported by adherents of Abrahamic religions based on a largely literal interpretation of their religious scriptural passages. The concept of uniformitarianism met with considerable resistance and the catastrophism vs. gradualism debate of the 19th century resulted. A variety of discoveries in the 20th century provided ample evidence that Earth history is a product of both gradual incremental processes and sudden cataclysmic events. Violent events such as meteorite impacts
Impact event
An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...
and large volcanic explosions do shape the Earth's surface along with gradual processes such as weathering
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
, erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
and deposition
Deposition (geology)
Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of...
much as they have throughout Earth history. The present is the key to the past - includes catastrophic as well as gradual processes.