The
history of geology is concerned with the development of the natural science of geology.
GeologyGeology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed...
is the scientific study of the origin, history, and structure of the
EarthEarth is the third planet from the Sun. It is the fifth largest of the eight planets in the solar system, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density...
. Throughout the ages geology provides essential theories and data that shape how society conceptualizes the Earth.
Antiquity
Some of the first geological thoughts were about the origin of the Earth. With a lack of knowledge and technology, ancient philosophers created
mythical storiesMythology is the study of myths and or of a body of myths. For example, comparative mythology is the study of connections between myths from different cultures, whereas Greek mythology is the body of myths from ancient Greece. The term "myth" is often used colloquially to refer to a false story;...
and proposed theories to explain how the Earth came to be. Ancient Greece developed some primary geological concepts concerning the origin of the Earth. Additionally, in the 4th century BC
AristotleAristotle was a Greek philosopher, a student of Plato and teacher of Alexander the Great. He wrote on many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, politics, government, ethics, biology, and zoology.Together with Plato and Socrates , Aristotle is one of...
made critical observations of the slow rate of geological change. He observed the composition of the land and formulated a theory where the Earth changes at a slow rate and that these changes cannot be observed during one person’s lifetime. Aristotle developed one of the first evidentially-based concepts connected to the geological realm regarding the rate at which the Earth physically changes.
However, it was his successor at the
LyceumA Lyceum can be*an educational institution , or*a public hall used for cultural events like concerts.*Mount Lyceum...
, the philosopher
TheophrastusTheophrastus , a Greek native of Eressos in Lesbos, was the successor of Aristotle in the Peripatetic school. His interests were wide-ranging, extending from biology and physics to ethics and metaphysics. His two surviving botanical works, Enquiry into Plants and On the Causes of Plants, were an...
, who made the greatest progress in antiquity in his work
On Stones. He described many minerals and
oresOrés is a municipality in the Cinco Villas, in the province of Zaragoza, in the autonomous community of Aragon, Spain. It belongs to the comarca of Cinco Villas. It is placed 104 km to the northwest of the provincial capital city, Zaragoza. Its coordinates are: 42° 17' N, 1° 00' W, and is located...
both from local mines such as those at
LauriumLaurium, Laurion, or Laureion is a town in southeastern part of Attica, Greece and is one of the southernmost and the seat of the municipality of Lavreotiki, famous in Classical antiquity for the silver mines which were one of the chief sources of...
near
AthensAthens , the capital and largest city of Greece, dominates the Attica periphery; as one of the world's oldest cities, its recorded history spans around 3,400 years....
, and further afield. He also quite naturally discussed types of
marbleMarble is a non foliated metamorphic rock resulting from the metamorphism of limestone, composed mostly of calcite . It is extensively used for sculpture, as a building material, and in many other applications...
and building materials like
limestoneLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geologic record...
s, and attempted a primitive classification of the properties of minerals by their properties such as hardness.
Much later in the
RomanAncient Rome was a civilization that grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC. Located along the Mediterranean Sea, it became one of the largest empires in the ancient world....
period,
Pliny the ElderGaius Plinius Secundus , better known as Pliny the Elder, was an author, naturalist, and natural philosopher as well as naval and army commander of the early Roman Empire and personal friend of the emperor Vespasian...
produced a very extensive discussion of many more minerals and
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
s then widely used for practical ends. He was among the first to correctly identify the origin of
amberAmber is fossilized tree resin , which has been appreciated for its color and natural beauty since neolithic times. Good quality amber is used for the manufacture of ornamental objects and jewelry...
as a fossilized
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
from trees by the observation of insects trapped within some pieces. He also laid the basis of
crystallographyCrystallography is the experimental science of determining the arrangement of atoms in solids. In older usage, it is the scientific study of crystals...
by recognising the octahedral habit of
diamondIn mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is the second most stable form of carbon, after graphite; however, the conversion rate from diamond to graphite is...
.
Middle Ages
Some modern scholars, such as
Fielding H. GarrisonColonel Fielding Hudson Garrison, MD was an acclaimed medical historian, bibliographer, and librarian of medicine. Garrison's An Introduction to the History of Medicine is a landmark text in this field....
, are of the opinion that modern geology began in the
medieval Islamic worldThe Islamic Golden Age or the Islamic Renaissance, is traditionally dated from the 9th to 13th centuries for 400 years C.E., but has been extended to the 15th century by recent scholarship...
.
GeberGeber is the Latinized form of "Jabir", with the full name of Abu Musa Jābir ibn Hayyān al azdi , a prominent polymath: a chemist and alchemist, astronomer and astrologer, engineer, geologist, philosopher, physicist, and pharmacist and physician...
(Jabir ibn Hayyan, 721-815 AD) is credited with the discovery of
crystallizationCrystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas...
as a purification process, an important contribution to
crystallographyCrystallography is the experimental science of determining the arrangement of atoms in solids. In older usage, it is the scientific study of crystals...
. Abu al-Rayhan al-Biruni (973-1048 AD) was one of the earliest
Muslim geologistsIslamic geography includes the advancement of geography, cartography and earth sciences under various Islamic civilizations. During the medieval ages, Islamic geography was driven by a number of factors: the Islamic Golden Age, parallel development of Islamic astronomy, translation of ancient texts...
, whose works included the earliest writings on the geology of India, hypothesizing that the
Indian subcontinentThe Indian subcontinent, also Indian Subcontinent and other terms, is a region of the Asian continent on the Indian tectonic plate south of the Himalayas, forming a peninsula which extends southward into the Indian Ocean...
was once a
seaA sea is any large amount of water filled with animals such as crabs, whales, sharks, and fish, but there is inconsistency as to its precise definition and application. Most commonly, a sea may refer to a large expanse of saline water connected with an ocean, but it is also used sometimes for a...
:
Ibn Sina, known as Abū Alī Sīnā or Ibn Sīnā , and commonly known in English by his Latinized name Avicenna , was a Persian polymath and the foremost physician and philosopher of his time...
(Avicenna, 981-1037), a Persian
polymathA polymath is a person whose expertise fills a significant number of subject areas. In less formal terms, a polymath may simply refer to someone who is very knowledgeable...
, made significant contributions to geology and the
natural scienceIn Science, the term natural science refers to a naturalistic approach to the study of the universe, which is understood as obeying rules or laws of natural origin...
s (which he called
Attabieyat) along with other natural philosophers such as
Ikhwan AI-SafaThe Brethren of Purity were a mysterious organization, whose identity has never been become clear, Muslim philosophers in Basra, Iraq - which was then the seat of the Abbasid Caliphate - sometime during the 10th century CE.Their esoteric teachings and philosophy are...
and many others. Ibn Sina wrote an encyclopaedic work entitled “
Kitab al-ShifaThe Book of Healing is a scientific and philosophical encyclopedia written by the Persian polymath Abū Alī ibn Sīnā from Asfahana, near Bukhara in Greater Persia...
” (the Book of Cure, Healing or Remedy from ignorance), in which Part 2, Section 5, contains his essay on Mineralogy and Meteorology, in six chapters: Formation of
mountainA mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them...
s, The advantages of mountains in the formation of
cloudA cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae...
s; Sources of
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
; Origin of
earthquakeAn earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph...
s; Formation of
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s; The diversity of earth’s
terrainTerrain, or relief, is the third or vertical dimension of land surface. When relief is described underwater, the term bathymetry is used...
. These principles were later known in the
RenaissanceThe Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Florence in the Late Middle Ages and later spreading to the rest of Europe...
of
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
as the
law of superpositionThe law of superposition is a key axiom based on observations of natural history that is a foundational principle of sedimentary stratigraphy and so of other geology dependent natural sciences:...
of strata, the concept of
catastrophismCatastrophism is the idea that Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope.The dominant paradigm of modern geology, in contrast, is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
, and the doctrine of
uniformitarianismUniformitarianism, in the philosophy of science, assumes 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...
. These concepts were also embodied in the Theory of the Earth by
James HuttonJames Hutton MD was a Scottish geologist, physician, naturalist, chemist and experimental farmer. He is considered the father of modern geology...
in the Eighteenth century C.E. Academics such as
ToulminStephen Edelston Toulmin is a British philosopher, author, and educator. Influenced by the Austrian born British philosopher Ludwig Wittgenstein, Toulmin devoted his works to the analysis of moral reasoning. Throughout his writings, he seeks to develop practical arguments which can be used...
and
GoodfieldJune Goodfield is a British scientist and writer of fiction and non-fiction.In September 2008 June Goodfield participated in the launch of a new personal and social history recording website called the Times of My Life...
(1965), commented on Avicenna's contribution: "Around A.D. 1000, Avicenna was already suggesting a hypothesis about the origin of mountain ranges, which in the Christian world, would still have been considered quite radical eight hundred years later". In particular, one of the principles underlying
geologic time scaleThe geologic time scale is a chronologic schema relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...
s was the
principle of superpositionThe law of superposition is a key axiom based on observations of natural history that is a foundational principle of sedimentary stratigraphy and so of other geology dependent natural sciences:...
of strata, first proposed by Ibn Sina. While discussing the origins of mountains in
The Book of HealingThe Book of Healing is a scientific and philosophical encyclopedia written by the Persian polymath Abū Alī ibn Sīnā from Asfahana, near Bukhara in Greater Persia...
in 1027, he outlined the principle as follows:
Ibn Sina's
scientific methodScientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific...
ology of
field observationA field experiment applies the scientific method to experimentally examine an intervention in the real world rather than in the laboratory...
was also original in the
Earth scienceEarth science , is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet...
s, and remains an essential part of modern geological investigations. His theory of
petrifyingIn geology, petrifaction, petrification or silicification is the process by which organic material is converted into stone by impregnation with silica. It is a rare form of fossilization...
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
s (
succus lapidificatus) was elaborated on
Albert of SaxonyAlbert of Saxony Albert of Saxony Albert of Saxony (Latin Albertus de Saxonia; (c. 1320 – 8 July 1390) was a German philosopher known for his contributions to logic and physics...
in the 14th century and was the dominant explanation of
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s by the 16th century.
In medieval
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
, one of the most intriguing
naturalistsNatural history is the scientific research of plants or animals, leaning more towards the observational than experimental methods of study, and encompasses more research that is published in magazines than in academic journals. Grouped among the natural sciences, Natural history is the systematic...
was
Shen KuoShen Kuo or Shen Gua , style name Cunzhong and pseudonym Mengqi Weng , was a polymathic Chinese scientist and statesman of the Song Dynasty...
(1031-1095), a
polymathA polymath is a person whose expertise fills a significant number of subject areas. In less formal terms, a polymath may simply refer to someone who is very knowledgeable...
personality who dabbled in many fields of study in his age. In terms of geology, Shen Kuo is one of the first naturalists to have formulated a theory of
geomorphologyGeomorphology is the scientific study of landforms and the processes that shape them...
. This was based on his observations of sedimentary uplift, soil erosion, deposition of
siltSilt is soil or rock derived granular material of a grain size between sand and clay. Silt may occur as a soil or as suspended sediment in a surface water body...
, and marine
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s found in the
Taihang MountainsThe Taihang Mountains are a Chinese mountain range running down the eastern edge of the Loess Plateau in Henan, Shanxi and Hebei provinces. The range extends over 400 km from north to south and has an average elevation of 1,500 to 2,000 meters. The principal peak is Xiao Wutaishan...
, located hundreds of miles from the
Pacific OceanThe Pacific Ocean is the largest of the Earth's oceanic divisions. Its name is derived from the Latin name Tepre Pacificum, "peaceful sea", bestowed upon it by the Portuguese explorer Ferdinand Magellan. It extends from the Arctic in the north to Antarctica in the south, bounded by Asia and...
. He also formulated a theory of gradual
climate changeClimate change is a change in the statistical distribution of weather over periods of time that range from decades to millions of years. It can be a change in the average weather or a change in the distribution of weather events around an average...
, after his observation of ancient petrified
bambooThe bamboos are a group of woody perennial evergreen plants in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Some are giant bamboos, the largest members of the grass family. Bamboos are the fastest growing woody plants in the world...
s found in a preserved state underground near Yanzhou (modern
Yan'anYan'an , is a Prefecture-level city in the Shanbei region of Shaanxi province in China, administering several counties, including Zhidan County, formerly Bao'an, which served as the Chinese communist capital before the city of Yan'an proper took that role....
), in the dry northern climate of
Shaanxi' is a province in the Northwest China region of the People's Republic of China, and includes portions of the Loess Plateau on the middle reaches of the Yellow River as well as the Qinling Mountains across the southern part of the province.-Romanization and Name:By regular Hanyu Pinyin rules, if...
province. He formulated a hypothesis for the process of land formation: based on his observation of
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
shells in a geological
stratumIn geology and related fields, a stratum is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural forces. They may extend over...
in a mountain hundreds of miles from the ocean, he inferred that the land was formed by
erosionErosion is a gravity driven process that moves solids in the natural environment or their source and deposits them elsewhere...
of the
mountainA mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them...
s and by deposition of
siltSilt is soil or rock derived granular material of a grain size between sand and clay. Silt may occur as a soil or as suspended sediment in a surface water body...
.
Industrial Revolution
During the 17th century the heated debate between religion and science over the Earth’s origin further propelled interest in the Earth and brought about more systematic identification techniques of the Earth’s
strataIn geology and related fields, a stratum is a layer of rock or soil with internally consistent characteristics that distinguishes it from contiguous layers. Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural forces. They may extend over...
. The Earth’s strata can be defined as horizontal layers of rock having approximately the same composition throughout.
The popular mining industry during the 18th century both increased social interest and drove scientists to form more systematic and detailed studies of the composition of the Earth’s strata. From the increased societal interest of geology, in 1741 it became a specific field of study to be taught at the National Museum of Natural History in France. The controversial topic of the Earth’s origin continued to circulate between religious and scientific circles. Two feuding theories developed to explain the Earth’s origin with designated followers: the
NeptunistsNeptunism is a discredited and obsolete scientific theory of geology proposed by Abraham Werner in the late 18th century that proposed rocks formed from the crystallisation of minerals in the early Earth's oceans....
whose theory supported that of the Bible’s Great Flood and the
PlutonistsPlutonic theory is the geologic theory proposed by James Hutton around the turn of the 18th century that volcanic activity was the source of rocks on the surface of the Earth with forms we see today only arising after erosion or other gradual processes. It was named for Pluto, the ancient Roman god...
who believed the Earth gradually formed over an immeasurable amount of time.
The dialogue about the creation of the Earth occurring within the scientific community and the evidence being uncovered in
Civil EngineeringCivil engineering is a professional engineering discipline that deals with the design, construction and maintenance of the physical and naturally built environment, including works such as bridges, roads, canals, dams and buildings...
works during the 19th century drove the development of the
stratigraphical columnStratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
; many of the concepts behind this invention can be attributed to
William SmithWilliam Smith was an English geologist, credited with creating the first nationwide geological map. He is known as the "Father of English Geology", although recognition was very slow in coming...
,
Georges CuvierGeorges Léopold Chrétien Frédéric Dagobert Cuvier was a French naturalist and zoologist. Of humble working class origins, he belonged to a new class of self-made scholars who worked their way to the top of academe...
and Alexander Broignart. Also in this period, imperialism motivated countries to sponsor voyages of exploration to distant lands.
Charles DarwinCharles Robert Darwin FRS was an English naturalist who realised and presented compelling evidence that all species of life have evolved over time from common ancestors, through the process he called natural selection...
made geological observations on such a voyage, providing evidential support of his revolutionary theory of
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
. Again a religious debate ensued; two conflicting groups,
uniformitariansUniformitarianism, in the philosophy of science, assumes 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...
and
catastrophistsCatastrophism is the idea that Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope.The dominant paradigm of modern geology, in contrast, is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
, argued over the age of the Earth.
Charles LyellSir Charles Lyell, 1st Baronet, Kt, FRS was a British lawyer, geologist, and proponent of uniformitarianism. He was the foremost geologist of his day, and an influence on the young Charles Darwin.- Life :...
, an influential uniformitarian, published his book in 1830 the “Principles of Geology” which proposed that the Earth changes very gradually and is immeasurably old.
The theory of
Continental DriftContinental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...
was proposed in 1912 by
Alfred WegenerAlfred Lothar Wegener was a German scientist, geologist, and meteorologist.He is most notable for his theory of continental drift , proposed in 1915, which hypothesized that the continents were slowly drifting around the Earth...
. This idea, unaccepted at the time, suggested a method of continental movement that occurred throughout history. Supporting evidence of Continental Drift, including
seafloor spreadingSeafloor spreading occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....
and
paleomagnetismPaleomagnetism is the study of the record of the Earth's magnetic field preserved in various magnetic minerals through time. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies substantially in both orientation and intensity through time.A paleomagnetist is a...
, justified the theory of Continental Drift, which in the late 1960s was replaced and encompassed by
Plate TectonicsPlate tectonics is a theory which describes the large scale motions of Earth's lithosphere...
. In the latter half of the 20th century the approach to the study of geology changed to evaluating the Earth in a broader perspective. To coincide with this perspective, satellites were first used in the 1970s and are still currently in use by the
Landsat ProgramThe Landsat program is the longest running enterprise for acquisition of imagery of Earth from space. The first Landsat satellite was launched in 1972; the most recent, Landsat 7, was launched on April 15, 1999. The instruments on the Landsat satellites have acquired millions of images...
to produce images of the Earth that can be geologically studied.
17th century
It was not until the 17th century that geology made great strides in its development. At this time, geology became its own entity in the world of natural science. It was discovered by the Christian world that different translations of the
BibleThe Bible contains the central religious texts of Judaism and Christianity. Modern Judaism generally recognizes a single set of canonical books known as the Tanakh, or Hebrew Bible, as it is written almost entirely in the Hebrew language, with some small portions in Aramaic...
contained different versions of the biblical text. The one entity that remained consistent through all of the interpretations was that the Deluge had formed the world’s geology and geography. To prove the Bible’s authenticity, individuals felt the need to demonstrate with scientific evidence that the Great Flood had in fact occurred. With this enhanced desire for data came an increase in observations of the Earth’s composition, which in turn led to the discovery of
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s. Although theories that resulted from the heightened interest in the Earth’s composition were often manipulated to support the concept of the Deluge, a genuine outcome was a greater interest in the makeup of the Earth. Due to the strength of Christian beliefs during the 17th century, the theory of the origin of the Earth that was most widely accepted was
A New Theory of the EarthA New Theory of the Earth was a book written by William Whiston, in which he presented a description of the divine creation of the Earth and a posited global flood. He also postulated that the earth originated from the atmosphere of a comet and that all major changes in earth's history could be...
published in 1696, by
William WhistonWilliam Whiston , was an English theologian, historian, and mathematician. He is probably best known for his translation of the Antiquities of the Jews and other works by Josephus, his A New Theory of the Earth, and his Arianism.-Biography:Whiston was born to Josiah Whiston and Katherine Rosse at...
. Whiston used Christian reasoning to “prove” that the Great Flood had occurred and that the flood had formed the rock strata of the Earth.
18th century
From this increased interest in the nature of the Earth and its origin, came a rise in the interest of
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s and other components of the Earth’s
crustIn geology, a crust is the outermost solid shell of a rocky planet or moon, which is chemically distinct from the underlying mantle. The crusts of Earth, our Moon, Mercury, Venus, Mars, Io, and other planetary bodies have been generated largely by igneous processes, and these crusts are richer in...
. Moreover, the increasing commercial importance of
miningMining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash...
in Europe during the mid to late 18th century made the possession of accurate knowledge about
oreAn ore is a type of rock that contains minerals such as gemstones or metals that can be extracted through mining and refined for use. Samples of ore in the form of exceptionally beautiful crystals, exotic layering visible when sectioned or polished or metallic presentations such as large nuggets or...
s and their natural distribution essential. Scholars began to study the makeup of the Earth in a systematic manner, with detailed comparisons and descriptions not only of the land itself, but of the semi-precious
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
s that had such great value. For example, in 1774
Abraham Gottlob WernerAbraham Gottlob Werner , was a German geologist who set out a now obsolete theory about the stratification of the Earth's crust and coined the now obsolete word Neptunism.-Life:...
published the book “Von den äusserlichen Kennzeichen der Fossilien” (
On the External Characters of Minerals), which brought him widespread recognition because he presented a detailed system for identifying specific minerals based on external characteristics. The more efficiently that productive land for mining could be found and that the semi-precious metals could be identified, the more money that could be made. This drive for economic success fueled geology into the limelight and made it a popular subject to pursue. With an increased number of people studying it, came more detailed observations and more information about the Earth.
During the eighteenth century, the story of the history of the Earth; namely the religious concept versus factual evidence once again became a popular discussion in society. In 1749 the French naturalist Georges-Louis Leclerc, Comte de Buffon published his “Histoire Naturelle” in which he attacked the popular Christian concepts of Whiston and other Christian theorists on the topic of the
history of EarthThe history of the Earth describes the most important events and fundamental stages in the development of the planet Earth from its formation to the present day during the last 4.54 billion years. Nearly all branches of natural science have contributed to the understanding of the main events of the...
. From experimentation with cooling globes, he found that the age of the Earth was not 6,000 years as stated in the Bible, but rather 75,000 years. Another individual who attributed the history of the Earth to neither God nor the Bible was the philosopher
Immanuel KantImmanuel Kant was an 18th-century German philosopher from the Prussian city of Königsberg...
who published this concept in 1755 in his “Allgemeine Naturgeschichte und Theories des Himmels.” From the works of these educated men, as well as others, it became acceptable by the mid eighteenth century to question the age of the Earth. This questioning represented a turning point in the study of the Earth. It was now possible to study the history of the Earth from a scientific perspective rather than a religious one.
With science as a driving force behind the investigation of the Earth’s history, the study of geology could now become a distinct field of science. First, the terminology and definition of what geological study consisted of had to be determined. The term geology was first used professionally in publications by two Genevian naturalists,
Jean-Andre DelucJean-André Deluc was a Swiss geologist and meteorologist.He was born at Geneva, descended from a family which had emigrated from Lucca and settled at Geneva in the 15th century...
and
Horace-Benedict de Saussure200px|thumb|Portrait of Horace-Bénédict de Saussure Horace-Bénédict de Saussure was a Swiss aristocrat, physicist and Alpine traveller, often considered the founder of alpinism.-Life and work:Saussure was born in Conches, near Geneva, in 1740.His early interest in botanical studies led him...
. Geology was not well received as a term until it was used in the very popular encyclopedia, the “Encyclopedie,” published in 1751 by
Denis DiderotDenis Diderot was a French philosopher, art critic and writer. He was a prominent figure during the Enlightenment and is best known for serving as chief editor of and contributor to the Encyclopédie....
. Once the term was coined as the study of the Earth and its history, geology slowly became a more prevalent and recognized science of its own standing that could be taught as a field of study at educational institutions. In 1741 the most well-known institution in the field of natural history, the National Museum of Natural History in France designated the first teaching position specifically for geology. This was an important step in the further development of geology as a science and in the recognition of the importance of widely distributing this knowledge.
After the designation of geology as a specific field of study in an institution, this subject flourished in educated society. By the 1770s two feuding theories with designated followers were established. These contrasting theories explained how the rock layers of the Earth’s surface had formed. The German geologist, Abraham Werner proposed the theory that the Earth’s layers, including
basaltBasalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey.On Earth, most...
and
graniteGranite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as porphyry. Granites can be pink to dark gray or even black, depending on their...
, had formed as a precipitate from an ocean that covered the entire Earth, referring to the Deluge. Werner’s system was influential and those that believed his theory were known as
NeptunistsNeptunism is a discredited and obsolete scientific theory of geology proposed by Abraham Werner in the late 18th century that proposed rocks formed from the crystallisation of minerals in the early Earth's oceans....
. The Scottish naturalist,
James HuttonJames Hutton MD was a Scottish geologist, physician, naturalist, chemist and experimental farmer. He is considered the father of modern geology...
, argued against the theory of Neptunism. Hutton proposed the theory of
PlutonismPlutonic theory is the geologic theory proposed by James Hutton around the turn of the 18th century that volcanic activity was the source of rocks on the surface of the Earth with forms we see today only arising after erosion or other gradual processes. It was named for Pluto, the ancient Roman god...
; the Earth formed through the gradual solidification of a molten mass at a slow rate by the same processes that occurred throughout history and continues in present day. This led him to the conclusion that the Earth was immeasurably old and could not possibly fit within the limits of the Bible’s 6,000 years. Plutonists believed that volcanic processes were the chief agent in rock formation, not water from a Great Flood.
19th century
The Neptunists and Plutonists supplied necessary data to help complete the stratigraphical column in the early 19th century. The stratigraphical column can be defined as “the sequence of rock formations arranged according to their order of formation in time.”
William SmithWilliam Smith was an English geologist, credited with creating the first nationwide geological map. He is known as the "Father of English Geology", although recognition was very slow in coming...
,
Georges CuvierGeorges Léopold Chrétien Frédéric Dagobert Cuvier was a French naturalist and zoologist. Of humble working class origins, he belonged to a new class of self-made scholars who worked their way to the top of academe...
and Alexander Broignart can all be recognized for their roles during this century in furthering the concept of fossil-based
stratigraphyStratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
. The English mineral surveyor William Smith found empirically that fossils were a highly effective means of distinguishing between otherwise similar formations of the landscape. At about the same time, the French comparative anatomist
Georges CuvierGeorges Léopold Chrétien Frédéric Dagobert Cuvier was a French naturalist and zoologist. Of humble working class origins, he belonged to a new class of self-made scholars who worked their way to the top of academe...
realized that the relative ages of fossils could be determined from a geological standpoint; in terms of what layer of rock the fossils are located and the distance these layers of rock are from the surface of the Earth. Cuvier’s mineralogist colleague Alexandre Brogniart augmented Cuvier’s practices. Through the synthesis of these findings, Brogniart and Cuvier realized that different strata could be identified by fossil contents and thus each stratum could be assigned to a unique position in a sequence. After the publication of Cuvier and Broignart’s book, “Description Geologiques des Environs de Paris” in 1811, which outlined the concept of stratigraphy, came a great interest in this new method. Stratigraphy became very popular amongst geologists; many hoped to apply this concept to all the rocks of the Earth. During this century various geologists further refined the stratigraphical column to completion. For instance, in 1833 while
Adam SedgwickAdam Sedgwick was one of the founders of modern geology. He proposed the Devonian period of the geological timescale and later the Cambrian period. The latter proposal was based on work which he did on Welsh rock strata...
was mapping rocks that he had established were from the
CambrianThe Cambrian is the first geological period of the Paleozoic era, lasting from ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux...
Period,
Charles LyellSir Charles Lyell, 1st Baronet, Kt, FRS was a British lawyer, geologist, and proponent of uniformitarianism. He was the foremost geologist of his day, and an influence on the young Charles Darwin.- Life :...
was elsewhere suggesting a subdivision of the
TertiaryThe Tertiary is a term for a geologic period 65 million to 2.588 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
Period; whilst
Roderick MurchisonSir Roderick Impey Murchison, 1st Baronet KCB FRS was a British geologist who first described and investigated the Silurian system.- Early life and work :...
, mapping into
WalesWales is a country that is part of the United Kingdom, bordered by England to its east, and the Atlantic Ocean and Irish Sea to its west. It is also an elective region of the European Union...
from a different direction, was assigning the upper parts of Sedgewick's
Cambrian to the lower parts of his own
SilurianThe Silurian is a geologic period and system that extends from the end of the Ordovician period, about 443.7 ± 1.5 Ma , to the beginning of the Devonian period, about 416.0 ± 2.8 Ma . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
Period. The stratigraphical column was significant because it now supplied a method to assign a relative age of these rocks by slotting them into different positions in their stratigraphical sequence. This created a global approach to dating the age of the Earth and allowed for further correlations to be drawn from similarities found in the makeup of the Earth’s crust in various countries.
In early nineteenth-century Britain, catastrophism was adapted with the aim of reconciling geological science with religious traditions of the biblical Great Flood. In the early 1820s English geologists including
William BucklandThe Very Rev. Dr William Buckland DD FRS was an English geologist, palaeontologist and Dean of Westminster, who wrote the first full account of a fossil dinosaur...
and Adam Sedgwick interpreted "diluvial" deposits as the outcome of Noah's flood, but by the end of the decade they revised their opinions in favour of local inundations. Charles Lyell challenged catastrophism with the publication in 1830 of the first volume of his book
Principles of Geology which presented a variety of geological evidence from England, France, Italy and Spain to prove Hutton’s ideas of gradualism correct. He argued that most geological change had been very gradual in human history. Lyell provided evidence for Uniformitarianism; a geological doctrine that processes occur at the same rates in the present as they did in the past and account for all of the Earth’s geological features. Lyell’s works were popular and widely read, the concept of Uniformitarianism had taken a strong hold in geological society.
During the same time that the stratigraphical column was being completed,
imperialismImperialism, as defined by the dictionary of human geography, is “the creation and maintenance of an unequal economic, cultural and territorial relationship, usually between states and often in the form of an empire, based on domination and subordination.” Imperialism, in many ways, is described...
drove several countries in the early to mid 19th century to explore distant lands to expand their empires. This gave naturalists the opportunity to collect data on these voyages. In 1831 Captain
Robert FitzRoyVice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...
, given charge of the coastal
survey expedition of HMS BeagleThe second voyage of HMS Beagle from 27 December 1831 to 2 October 1836 was the second survey expedition of HMS Beagle, under captain Robert FitzRoy who had taken over command of the ship on its first voyage after her previous captain committed suicide...
, sought a suitable naturalist to examine the land and give geological advice. This fell to
Charles DarwinCharles Robert Darwin FRS was an English naturalist who realised and presented compelling evidence that all species of life have evolved over time from common ancestors, through the process he called natural selection...
, who had just completed his BA degree and had accompanied Sedgwick on a two week Welsh mapping expedition after taking his Spring course on geology. Fitzroy gave Darwin Lyell’s
Principles of Geology, and Darwin became Lyell's first disciple, inventively theorising on
uniformitarianUniformitarianism, in the philosophy of science, assumes 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...
principles about the geological processes he saw, and challenging some of Lyell's ideas. He speculated about the Earth expanding to explain uplift, then on the basis of the idea that ocean areas sank as land was uplifted, theorised that coral atolls grew from fringing
coral reefCoral reefs are aragonite structures produced by living organisms, found in marine waters containing few nutrients. In most reefs, the predominant organisms are stony corals, colonial cnidarians that secrete an exoskeleton of calcium carbonate...
s round sinking volcanic islands. This idea was confirmed when the
Beagle surveyed the
Cocos (Keeling) IslandsThe Territory of Cocos Islands, also called Cocos Islands and Keeling Islands, is a territory of Australia. There are two atolls and twenty-seven coral islands in the group...
. Darwin's discovery of giant fossils helped to establish his reputation as a geologist, and his theorising about the causes of their extinction led to his theory of
evolutionIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are normally small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a...
by
natural selectionNatural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations...
published in
On the Origin of Species in 1859.
Economic motivations for the practical use of geological data caused governments to support geological research. During the 19th century the governments of several countries including Canada, Australia, Great Britain and the United States funded geological surveying that would produce geological maps of vast areas of the countries. Geological surveying provides the location of useful minerals and such information could be used to benefit the country’s mining industry. With the government funding of geological research, more individuals could study geology with better technology and techniques, leading to the expansion of the field of geology.
In the 19th century, scientific realms established the age of the Earth in terms of millions of years. By the early 20th century the Earth’s estimated age was 2 billion years.
Radiometric datingRadiometric dating is a technique used to date materials, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
determined the age of minerals and rocks, which provided necessary data to help determine the Earth’s age. With this new discovery based on verifiable scientific data and the possible age of the Earth extending billions of years, the dates of the geological time scale could now be refined. Theories that did not comply with the scientific evidence that established the age of the Earth could no longer be accepted.
20th century
The determined age of the Earth as 2 billion years opened doors for theories of continental movement during this vast amount of time. In 1912
Alfred WegenerAlfred Lothar Wegener was a German scientist, geologist, and meteorologist.He is most notable for his theory of continental drift , proposed in 1915, which hypothesized that the continents were slowly drifting around the Earth...
proposed the theory of
Continental DriftContinental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...
. This theory suggests that the continents were joined together at a certain time in the past and formed a single landmass known as
PangaeaPangaea, Pangæa, or Pangea was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration.The name was first used by the German originator of the continental...
; thereafter they drifted like rafts over the ocean floor, finally reaching their present position. The shapes of continents and matching coastline geology between some continents indicated they were once attached together as Pangea. Additionally, the theory of continental drift offered a possible explanation as to the formation of mountains. From this, different theories developed as to how mountains were built. Unfortunately, Wegner’s ideas were not accepted during his lifetime and his theory of Continental Drift was not accepted until the 1960s.
In the 1960s new found evidence supported the theory of Continental Drift. The term Continental Drift was no longer used but was replaced by the concept of
Plate TectonicsPlate tectonics is a theory which describes the large scale motions of Earth's lithosphere...
that was well supported and accepted by almost all geologists by the end of the decade. Geophysical evidence suggested lateral motion of continents and that
oceanic crustOceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima...
is younger than continental crust. This geophysical evidence also spurred the hypotheses of
seafloor spreadingSeafloor spreading occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....
and
paleomagnetismPaleomagnetism is the study of the record of the Earth's magnetic field preserved in various magnetic minerals through time. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies substantially in both orientation and intensity through time.A paleomagnetist is a...
. The hypothesis of seafloor spreading, proposed by
Robert S. DietzRobert Sinclair Dietz was Professor of Geology at Arizona State University. Dietz was a geophysicist and oceanographer who conducted pioneering research along with Harry Hess concerning seafloor spreading as early as 1960 - 1961...
and Harry H. Hess, holds that the oceanic crust forms as the seafloor spreads apart along
mid-ocean ridgeA mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading center, which is responsible for seafloor...
s. Paleomagnetism is the record of the orientation of the Earth’s
magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
recorded in magnetic minerals. British geophysicist S. Runcorm suggested the concept of paleomagnetism from his finding that the continents had moved relative to the Earth’s magnetic poles.
Modern geology
By applying sound stratigraphic principles to the distribution of
cratersIn the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
on the
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
, it can be argued that almost overnight,
Gene ShoemakerEugene Merle Shoemaker was one of the founders of the fields of planetary science....
took the study of the Moon away from Lunar astronomers and gave it to
Lunar geologistsThe geology of the Moon is quite different from that of the Earth...
.
In recent years, geology has continued its tradition as the study of the character and origin of the Earth, its surface features and internal structure. What changed in the later 20th century is the perspective of geological study. Geology was now studied using a more integrative approach, considering the Earth in a broader context encompassing the atmosphere, biosphere and hydrosphere. Satellites located in space that take wide scope photographs of the Earth provide such a perspective. In 1972, The Landsat Program, a series of satellite missions jointly managed by
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
and the U.S. Geological Survey, began supplying satellite images that can be geologically analyzed. These images can be used to map major geological units, recognize and correlate rock types for vast regions and track the movements of Plate Tectonics. A few applications of this data include the ability to produce geologically detailed maps, locate sources of natural energy and predict possible natural disasters caused by plate shifts.
See also
- 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...
- Flood geology
Flood geology is the attempt to confirm the literal truth of the flood narrative in Genesis 6–9...
- Geology
Geology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed...
- Geodesy
Geodesy , also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space. Geodesists also study geodynamical phenomena such as crustal...
- Geography
Geography is the study of the Earth and its lands, features, inhabitants, and phenomena. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
- Historical geology
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...
- Geological history of Earth
The geological history of Earth began 4.567 billion years ago when the planets of the Solar System were formed out of the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun. Initially molten, the outer layer of the planet Earth cooled to form a solid...
- History of palaeontology
- History of science
Science is a body of empirical, theoretical, and practical knowledge about the natural world, produced by a global community of researchers making use of scientific methods, which emphasize the observation, explanation, and adequate prediction of real world phenomena by experiment...
- Humboldtian science
Humboldtian science is a term given to the movement in science in the 19th century. The ideals and central themes of Humboldtian science are the result of the work of German scientist Alexander von Humboldt...
- Natural history
Natural history is the scientific research of plants or animals, leaning more towards the observational than experimental methods of study, and encompasses more research that is published in magazines than in academic journals. Grouped among the natural sciences, Natural history is the systematic...
- Natural philosophy
Natural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
- Nicolas Steno
Nicolas Steno was a Danish pioneer in both anatomy and geology. Already in 1659 he decided not to accept anything simply written in a book, instead resolving to do research himself...
External links
- http://geology.com
- http://landsat.gsfc.nasa.gov