The Geologist - Carl Spitzweg, circa 1860
| Seismologist |
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes the Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, although backgrounds in physics, chemistry, biology, and other sciences are also useful. Field work is an important component of geology, although many subdisciplines incorporate laboratory work.
Geologists work in the energy and mining sectors searching for natural resources such as petroleum, natural gas, precious and base metals. They are also in the forefront of preventing and mitigating damage from natural hazards and disasters such as earthquakes, volcanoes, tsunamis and landslides. Their studies are used to warn the general public of the occurrence of these events. Geologists are also important contributors to climate change discussions.
James Hutton is often viewed as the first modern geologist.In 1785 he presented a paper entitled Theory of the Earth to the Royal Society of Edinburgh. In his paper, he explained his theory that the Earth must be much older than had previously been supposed to allow enough time for mountains to be eroded and for sediments to form new rocks at the bottom of the sea, which in turn were raised up to become dry land. Hutton published a two-volume version of his ideas in 1795 (Vol. 1, Vol. 2). Followers of Hutton were known as Plutonists because they believed that some rocks were formed by vulcanism, which is the deposition of lava from volcanoes, as opposed to the Neptunists , led by Abraham Werner, who believed that all rocks had settled out of a large ocean whose level gradually dropped over time.
The first geological map of the United States was produced in 1809 by William Maclure.In 1807, Maclure commenced the self-imposed task of making a geological survey of the United States. Almost every state in the Union was traversed and mapped by him; the Allegheny Mountains being crossed and recrossed some 50 times. The results of his unaided labors were submitted to the American Philosophical Society in a memoir entitled Observations on the Geology of the United States explanatory of a Geological Map, and published in the Society's Transactions, together with the nation's first geological map. This antedates William Smith's geological map of England by six years, although it was constructed using a different classification of rocks.
Sir Charles Lyell first published his famous book, Principles of Geology ,in 1830. This book, which influenced the thought of Charles Darwin, successfully promoted the doctrine of uniformitarianism. This theory states that slow geological processes have occurred throughout the Earth's history and are still occurring today. In contrast, catastrophism is the theory that Earth's features formed in single, catastrophic events and remained unchanged thereafter. Though Hutton believed in uniformitarianism, the idea was not widely accepted at the time.
For an aspiring geologist, training typically includes significant coursework in physics, mathematics, and chemistry, in addition to classes offered through the geology department; historical and physical geology, igneous and metamorphic petrology and petrography, hydrogeology, sedimentology, stratigraphy, mineralogy, palaeontology, physical geography and structural geology are among the many required areas of study. Most geologists also need skills in GIS and other mapping techniques. Geology students often spend portions of the year, especially the summer though sometimes during a January term, living and working under field conditions with faculty members (often referred to as "field camp"). Many non-geologists often take geology courses or have expertise in geology that they find valuable to their fields; this is common in the fields of geography, engineering, chemistry, urban planning, environmental studies, among others.
Geologists may concentrate their studies or research in one or more of the following disciplines:
Professional geologists work for a wide range of government agencies, private firms, and non-profit and academic institutions. They are usually hired on a contract basis or hold permanent positions within private firms or official agencies (such as the United States Geologic Survey).
Local, state, and national governments hire geologists to work on geological projects that are of interest to the public community. The investigation of a country's natural resources is often a key role when working for government institutions; the work of the geologist in this field can be made publicly available to help the community make more informed decisions related to the exploitation of resources, management of the environment and the safety of critical infrastructure - all of which is expected to bring greater wellbeing to the country.This 'wellbeing' is often in the form of greater tax revenues from new or extended mining projects or through better infrastructure and/or natural disaster planning.
An engineering geologist is employed to investigate geologic hazards and geologic constraints for the planning, design and construction of public and private engineering projects, forensic and post-mortem studies, and environmental impact analysis. Exploration geologists use all aspects of geology and geophysics to locate and study natural resources. In many countries or U.S. states without specialized environmental remediation licensure programs, the environmental remediation field is often dominated by professional geologists, particularly hydrogeologists, with professional concentrations in this aspect of the field. Petroleum and mining companies use mudloggers, and large-scale land developers use the skills of geologists and engineering geologists to help them locate oil and minerals, adapt to local features such as karst topography or earthquake risk, and comply with environmental regulations.
Geologists in academia usually hold an advanced degree in a specialized area within their geological discipline and are employed by universities.
In Canada, National Instrument 43-101 requires reports containing estimates of mineral resources and reserves to be prepared by, or under the supervision of, a Qualified Person (QP) who has at least five years of experience with the reported minerals and is a member of a professional association. The QP accepts personal liability for the professional quality of the report and underlying work.
The rules and guidelines codified in National Instrument 43-101 were introduced after a scandal in 1997 where Bre-X geologists salted drill core samples at a gold exploration property in Busang, Indonesia. The falsified drilling results misled Bre-X investors and upon discovery of the fraud, the company collapsed in the largest gold mining scam in history.
Geology is an Earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology significantly overlaps all other Earth sciences, including hydrology and the atmospheric sciences, and so is treated as one major aspect of integrated Earth system science and planetary science.
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat and pressure, causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock.
Neptunism is a superseded scientific theory of geology proposed by Abraham Gottlob Werner (1749–1817) in the late 18th century, proposing that rocks formed from the crystallisation of minerals in the early Earth's oceans.
Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation, transport, deposition and diagenesis. Sedimentologists apply their understanding of modern processes to interpret geologic history through observations of sedimentary rocks and sedimentary structures.
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 two related subfields: lithostratigraphy and biostratigraphy.
A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed. Rocks are usually grouped into three main groups: igneous rocks, metamorphic rocks and sedimentary rocks. Rocks form the Earth's outer solid layer, the crust.
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, natural gas, coal, and water. Economic geology is a subdiscipline of the geosciences; according to Lindgren (1933) it is “the application of geology”. Today, it may be called the scientific study of the Earth's sources of mineral raw materials and the practical application of the acquired knowledge. The term commonly refers to metallic mineral deposits and mineral resources. The techniques employed by other earth science disciplines might all be used to understand, describe, and exploit an ore deposit.
Petrology is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock.
This is a list of all articles related to geology that cannot be readily placed on the following subtopic pages:
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788.
Relative dating is the science of determining the relative order of past events, without necessarily determining their absolute age. In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another. Prior to the discovery of radiometric dating in the early 20th century, which provided a means of absolute dating, archaeologists and geologists used relative dating to determine ages of materials. Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique. Relative dating by biostratigraphy is the preferred method in paleontology and is, in some respects, more accurate. The Law of Superposition, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.
Chemostratigraphy, or chemical stratigraphy, is the study of the chemical variations within sedimentary sequences to determine stratigraphic relationships. The field is relatively young, having only come into common usage in the early 1980s, but the basic idea of chemostratigraphy is nearly as old as stratigraphy itself: distinct chemical signatures can be as useful as distinct fossil assemblages or distinct lithographies in establishing stratigraphic relationships between different rock layers.
The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,200 mi) long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton, began to split apart during the Mesoproterozoic era of the Precambrian, about 1.1 billion years ago. The rift failed, leaving behind thick layers of igneous rock that are exposed in its northern reaches, but buried beneath later sedimentary formations along most of its western and eastern arms. Those arms meet at Lake Superior, which is contained within the rift valley. The lake's north shore in Ontario and Minnesota defines the northern arc of the rift. From the lake, the rift's eastern arm trends south to central lower Michigan, and possibly into Indiana, Ohio, Kentucky, Tennessee, and Alabama. The western arm runs from Lake Superior southwest through portions of Wisconsin, Minnesota, Iowa, and Nebraska to northeastern Kansas, and possibly into Oklahoma.
The following outline is provided as an overview of and topical guide to geology:
Igneous petrology is the study of igneous rocks—those that are formed from magma. As a branch of geology, igneous petrology is closely related to volcanology, tectonophysics, and petrology in general. The modern study of igneous rocks utilizes a number of techniques, some of them developed in the fields of chemistry, physics, or other earth sciences. Petrography, crystallography, and isotopic studies are common methods used in igneous petrology.
Earth Revealed: Introductory Geology, originally titled Earth Revealed, is a 26-part video instructional series covering the processes and properties of the physical Earth, with particular attention given to the scientific theories underlying geological principles. The telecourse was produced by Intelecom and the Southern California Consortium, was funded by the Annenberg/CPB Project, and first aired on PBS in 1992 with the title Earth Revealed. All 26 episodes are hosted by Dr. James L. Sadd, professor of environmental science at Occidental College in Los Angeles, California.
Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical and chemical constitution of the Earth and its atmosphere. Earth science can be considered to be a branch of planetary science, but with a much older history. Earth science encompasses four main branches of study, the lithosphere, the hydrosphere, the atmosphere, and the biosphere, each of which is further broken down into more specialized fields.
A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest rocks on the bottom and the youngest on top.
Dollie Radler Hall was one of the first female geologists in Oklahoma. In 1921, she earned her master's degree from the University of Oklahoma in the field of Geology. Dollie was married to Charlie Hall, her childhood sweetheart. Though she faced professional exclusion as one of the only female geologists in her field, she followed through in pursuing Geology as her field of study.