Carbonate Petrography

Carbonate petrography is the study of limestones, dolomites and associated deposits under optical or electron microscopes greatly enhances field studies or core observations and can provide a frame of reference for geochemical studies.

25 strangest Geologic Formations on Earth

The strangest formations on Earth.

What causes Earthquake?

Of these various reasons, faulting related to plate movements is by far the most significant. In other words, most earthquakes are due to slip on faults.

The Geologic Column

As stated earlier, no one locality on Earth provides a complete record of our planet’s history, because stratigraphic columns can contain unconformities. But by correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a composite stratigraphic column, called the geologic column, that represents the entirety of Earth history.

Folds and Foliations

Geometry of Folds Imagine a carpet lying flat on the floor. Push on one end of the carpet, and it will wrinkle or contort into a series of wavelike curves. Stresses developed during mountain building can similarly warp or bend bedding and foliation (or other planar features) in rock. The result a curve in the shape of a rock layer is called a fold.

Geology Degree

Geology Degree

As a geology graduate, your mastery in undertaking field and lab examinations joined with your team-working, correspondence and systematic abilities make you an alluring prospect for some businesses.

Definition of Geology

Geology is a science that studies the Earth and the materials that it’s made of. It looks at the rocks that the Earth is composed of, the structure of the earth’s materials, and the processes acting upon those materials that cause the Earth to evolve. Through the study of geology we can understand the history of the Earth. Geologists decipher evidence for plate tectonics, the evolutionary history of life, and the past climates the Earth has been through. Geology also includes the study of organisms that have inhabited the planet, and how they’ve changed over time.

Currently we use geology for mineral and hydrocarbon exploration, evaluating water resources, predicting natural hazards, finding remedies for environmental problems, providing insights into past climate change, and geotechnical engineering. Through geology degrees people can study geology, become a geologist, and use their knowledge to improve our Earth.

A Geology Degree

If you’re interested in studying geology, there are a few different degree options open to you in both undergrad and graduate education. The following are a few options:
  • Bachelor of Arts in Geology: The BA in geology degree is intended for students who plan to pursue teacher certification, natural resource management, scientific or technical writing, and other fields that combine a strong liberal arts background with science training. BA classes may include earth materials, minerals, igneous and metamorphic rocks, oceanography, principles of astronomy, deformation of the Earth, sedimentary processes, earth surface processes, and field methods.
  • Bachelor of Science in Geology: The BS in geology degree differs from the BA in that it has a strong mathematical component. It’s typically designed for students planning to pursue graduate study in geology, or work as a professional geologist. Courses may include: History of the Earth, Earth materials, deformation of the Earth, sedimentary processes, Earth surface processes, field methods, chemistry, physics, physics in electricity and magnetism, and calculus classes.
  • Master of Science in Geology: This is a graduate degree in geology. Master programs are advanced geology degrees with a focus on geology classes. They typically come in both thesis and non-thesis options. Those who want to get a master’s in geology degree must have an undergraduate degree in geology or a closely related science field. Sometimes they’ll let applicants without a bachelor’s degree in geology to take pre-requisite classes before beginning a master’s program. Pre-requisite classes include: physical geology, mineralogy, paleobiology, petrography, geologic field methods, stratigraphy, igneous/metamorphic petrogenesis, structural geology, sedimentary petrogenesis, and introduction to geophysics.
  • Doctorate in Geology: A PhD is the highest level of degree a person can get in geology. These programs are designed to develop creative scholarship and to prepare the student for a professional career in the geological sciences. Typically a person chooses a specialisation or focus such as geochemistry, geology, geophysics, planetary geology, minerals, or more. Students can be admitted into PhD programs with either a bachelor’s or master’s degree in geology. Depending on the previous degree earned, a PhD may take one to two years of study.
In all degree levels of geology, the goal is for students to master basic concepts and vocabulary in geology. Through these programs you’ll learn the following materials:
  • Plate tectonics
  • Origin and classification of rocks and minerals
  • Geological time scale and how this relates to major events in the history of Earth and its life
  • Geophysical properties of the Earth and crustal deformation
  • Processes that shape the surface of the Earth
  • Environmental hazards and issues
You’ll also be expected to:
  • Develop skills in observing and recording geologic features and processes
  • Develop competency in the interpretation of earth science data, including both qualitative and quantitative analyses
  • Achieve competence in: locating and interpreting scientific literature,
  • Giving oral presentations,
  • Using computers at a level consistent with current professional practice
  • Be able to express earth science concepts in writing

Specializations Within Geology

Not all geologists study the same thing. Since the Earth is so large there are many areas that a geologist can focus on. The following are the most common types of geology specialisations within geology degrees:
  • Economic Geology: These geologists help locate and manage the Earth’s natural resources. These resources may include petroleum, coal, and minerals such as iron, copper, and uranium. Typically these resources are used for profit companies.
  • Mining Geology: This is a common form of geology that focuses on extracting mineral resources from the Earth. Typically these resources are of economic interest. They may include gemstones, metals, and many minerals such as asbestos, perlite, mica, phosphates, zeolites, clay, pumice, quartz, silica, sulphur, chlorine, and helium.
  • Petroleum Geology: These geologists study locations below the Earth’s surface where extractable hydrocarbons may be. They especially focus on petroleum and natural gas. Petroleum geologists also study the formation of sedimentary basins, where gas reservoirs are typically found. They look into the sedimentary and tectonic evolution, and the present-day positions of rocks within the basins.
  • Engineering Geology: This is the application of geologic principles to engineering practice. The main purpose of engineering geology is to assure that the geologic factors affecting the location, design, construction, operation, and maintenance of engineering works are properly addressed in engineering and building projects. In civil engineering geological principles are used in order to analyse the mechanical principles of the material on which structures are built, or will be built. This allows tunnels to be built without collapsing, and bridges and skyscrapers to be built with sturdy foundations.
  • Environmental Geology: Geology can be applied to various environmental problems. It can be applied in steam restoration, the restoration of brownfield, the understanding of the interactions between natural habitat and the geologic environment, and more.
  • Hydrology Geology: Groundwater hydrology, or hydrogeology, is used to locate groundwater. This can often provide a ready supply of uncontaminated water and is especially important in arid regions. It’s also used to monitor the spread of contaminants in groundwater wells.
  • Natural Hazards Geology: Geologists study natural hazards in order to enact safe building codes. They also make warning systems that are used to prevent loss of property and life amidst natural hazards. The kind of natural hazards that geologists’ study include: avalanches, earthquakes, floods, landslides, debris flows, river channel migration, avulsion, liquefaction, sinkholes, subsidence, tsunamis, and volcanoes.

Day in a Life of a Geologist

In general, geologists work to understand the history of our planet. As noted above, there are many different types of geology that geologists can focus on. The better understanding geologists have of the Earth’s history, the better they can foresee how events and processes of the past and present may influence the future. We rely on geologists to find a good supply of Earth’s products, such as natural gases and minerals. Every structure that we build we must know about the ground it sits on. Our food and fibre comes from soil, which we must understand to produce food. Protection against geologic hazards also depends on a geologists’ understanding of them.
Geologists are responsible for many important contributions to society. In fact, we rely on them in everyday life without even realising it. Geologists use a number of field, laboratory, and numerical modelling methods to decipher Earth history. Through geological investigations, geologists use primary information related to the study of rocks (petrology), sedimentary layers (stratigraphy), and positions of rocks and their deformation (structural geology). In many cases, geologists also study modern soils, rivers, landscapes, and glaciers. They investigate past and current life and biogeochemical pathways, and use geophysical methods to investigate the subsurface of the Earth. The following are the typical categories that geologist’s work fall under:
  • Earth processes: The Earth is constantly evolving and changing due to natural disasters and climate change. These include landslides, earthquakes, floods and volcanic eruptions, all of which can be hazardous to people. Some geologists’ jobs are to understand these processes. Through understanding them they help build important structures where they won’t be damaged, or create maps of areas that have flooded in the past and that could be flooded in the future. These kinds of maps can be used in developing communities and housing areas. They can determine if certain houses need flood insurance or protection.
  • Earth materials: Humans use the Earth’s materials on a daily basis. We use oil that’s produced from wells, metals produced from mines, water drawn from underground sources, and more. A geologist’s work could involve studying rocks that contain important metals, finding and planning mines that could produce metals, finding oil reservoirs, and more.
  • Earth History: A current issue for our world is climate change. Many geologists are currently working to learn more about past climates of the Earth and how they’ve changed over time. Through understanding these patterns, geologists can understand our current climate change and what the future results of that change may be.

Job Options


Occupations specifically identified with your degree include:
  • Building geologist 
  • Geochemist 
  • Geophysicist/field seismologist 
  • Geoscientist 
  • Hydrogeologist 
  • Seismic mediator 
  • Mudlogger 
  • Wellsite geologist 
Occupations where your degree would be helpful include:
  • Drilling Engineer
  • Ecological specialist 
  • Geophysical information processor 
  • Minerals surveyor 
Keep in mind that numerous businesses acknowledge applications from graduates with any degree subject, so don't confine you're supposing to the employments recorded here.

Work Experience

Hands on work in both the UK and abroad is a key a portion of topography courses as it gives down to earth experience. A few courses offer a year out, either abroad or in industry, an awesome chance to expand your ability set and build up a system of contacts.
A few graduates decide to improve their capabilities and abilities by doing paid or intentional deal with fleeting natural tasks in the UK or abroad. Time getting work experience or shadowing can assist you with settling on choices about your future vocation and you'll see it inspiring when you apply your ability to tackle issues in an alternate connection.

Typical Employers

Numerous geography graduates enter callings specifically identified with their degree. Prominent parts incorporate investigation and creation, water supply, natural building and topographical looking over. Different regions incorporate ecological arranging, hydrogeology and contamination control. Average managers of geography graduates include: 
  • the oil, gas and petroleum area; 
  • the groundwater business; 
  • ecological consultancies; 
  • structural building and development organisations.

Skills for your CV

Considering geography you'll increase particular learning identified with your project of study and module decisions. The down to earth field work you do as a major aspect of your degree outfits you with ability in field and research facility examinations. 

Transferable aptitudes from your course include: 
  • aptitudes in perception, information gathering, examination and elucidation; 
  • the capacity to get ready, process and present information; 
  • the capacity to handle data in a scope of distinctive mediums, e.g. literary, numerical, oral, graphical; 
  • composed and verbal relational abilities; 
  • report composing abilities; 
  • critical thinking aptitudes and horizontal considering; 
  • self-inspiration and flexibility; 
  • team-working aptitudes and the capacity to deal with your own particular activity.

Further Study

Further study is a prevalent alternative for geography graduates. In case you're keen on getting into a specific field of geography, for example, mining building, designing topography or the minerals business, what about taking an applicable M.Sc course? 
For instance, taking a M.Sc in petroleum geoscience is a possibility for those needing to get into the petroleum business. Different cases of postgraduate courses include:
  • petroleum engineering;
  • petroleum geophysics;
  • earth sciences;
  • hydrogeology;
  • waste management;
  • nuclear decommissioning.
A little number of understudies proceed onto PhD. By learning at postgraduate level, you'll build up your authority information, research aptitudes and relational abilities.

Rock layers

Rock layers


In geology and related fields, a stratum (plural: strata) is a sedimentary rock layer or soil with inside reliable qualities that recognize it from different rock layers. The "stratum" is the crucial unit in a stratigraphic section and structures the study's premise of stratigraphy.

Characteristics of rock layers

Every rock layer is for the most part one of various parallel rock layers that lie one upon another, set around characteristic procedures. They may stretch out over a huge number of square kilometres of the Earth's surface. Strata are normally seen as groups of diverse shaded or contrastingly organized material uncovered in bluffs, street cuts, quarries, and waterway banks. Individual groups may fluctuate in thickness from a couple of millimetres to a kilometre or more. Every band speaks to a particular method of affidavit: stream residue, shoreline sand, coal bog, sand ridge, magma bed, and so on.

Naming of rock layers

Geologists study rock strata and sort them by the material of beds. Each particular layer is normally doled out to the name of sheet, generally in view of a town, stream, mountain, or locale where the arrangement is uncovered and accessible for study. For instance, the Burgess Shale is a thick introduction of dim, once in a while fossiliferous, shale uncovered high in the Canadian Rockies close Burgess Pass. Slight refinements in material in an arrangement may be portrayed as "individuals" (or now and again "beds"). Arrangements are gathered into "gatherings" while gatherings may be gathered into "supergroups".

Formation

An formation or geological formation is the basic unit of lithostratigraphy. An arrangement comprises of a sure number of rock strata that have an equivalent lithology, facies or other comparable properties. Developments are not characterized on the stone's thickness strata they comprise of and the thickness of distinctive formation can thus change broadly. 
The idea of formally characterized layers or strata is key to the geologic control of stratigraphy. Arrangements can be separated into individuals and are themselves regularly divided in gatherings.

Usefulness of formation

The definition and acknowledgement of formations permit geologists to correspond geologic strata crosswise over wide separations in the middle of outcrops and exposures of rock strata. 

Developments were at first depicted to be the crucial geologic time markers in view of relative ages and the law of superposition. The divisions of the land time scale were the formations depicted and put in sequential request by the geologists and stratigraphers of the eighteenth and nineteenth hundreds of years. 

Current modification of the geologic sciences has limited formations to lithologies, in light of the fact that lithological units are shaped by depositional situations, some of which may continue for a huge number of years and will transgress chronostratigraphic interims or fossil-based routines for relating rocks. For instance, the Hamersley Basin of Western Australia is a Proterozoic sedimentary bowl where up to 1200 million years of sedimentation is saved inside of the in place sedimentary stratigraphy, with up to 300 million years spoke to by a solitary lithological unit of grouped iron arrangement and shale. 

Geologic developments are typically sedimentary rock layers, yet might likewise be transformative rocks and volcanic streams. Molten nosy rocks are for the most part not separated into formations.

Defining lithostratigraphic formations

Formations are the main formal lithostratigraphic units into which the stratigraphic section all over ought to be partitioned totally on the premise of lithology. 

The difference in lithology between arrangements required to legitimize their foundation shifts with the multifaceted nature of the geography of an area and the point of interest required for geologic mapping and to work out its geologic history. 

Formations must have the capacity to be depicted at the size of geologic mapping honed in the area. The thickness of developments may run from not as much as a meter to a few thousand meters. 

Geologic arrangements are normally named for the geographic territory in which they were initially portrayed. 

Entirely, developments can't be characterized on whatever other criteria aside from essential lithology. Nonetheless, it is frequently helpful to characterize biostratigraphic units in light of paleontological criteria, chronostratigraphic units taking into account the stones' age, and chemostratigraphic units in view of geochemical criteria. 

Succession stratigraphy is an idea which challenges the thought of strict lithostratigraphic units by characterizing units in light of occasions in sedimentary bowls, for example, maritime relapses and transgressions. These groupings are a mix of chronostratigraphic units, connected by time, and depositional environment connected by the geologic occasions which happened around then, paying little respect to the grain size of the silt. 

The expression "formation" is regularly utilized casually to allude to a particular gathering of rocks, for example, those experienced inside of a sure profundity range in an oil well.

What is Earth made of?

What is Earth made of?

The proportions of major elements making up the mass of the whole Earth.
At this point, we leave our fantasy space voyage and turn our attention inward to the materials that make up the solid Earth, because we need to be aware of these before we can discuss the architecture of the Earth’s interior. Let’s begin by reiterating that the Earth consists mostly of elements produced by fusion reactions in stars and by supernova explosions. Only four elements (iron, oxygen, silicon, and magnesium) make up 91.2% of the Earth’s mass; the remaining 8.8% consists of the other 88 elements (figure above). The elements of the Earth comprise a great variety of materials.
  • Organic chemicals. Carbon-containing compounds that either occur in living organisms or have characteristics that resemble compounds in living organisms are called organic chemicals. 
  • Minerals. A solid, natural substance in which atoms are arranged in an orderly pattern is a mineral. A single coherent sample of a mineral that grew to its present shape is a crystal, whereas an irregularly shaped sample, or a fragment derived from a once-larger crystal or cluster of crystals, is a grain. 
  • Glasses. A solid in which atoms are not arranged in an orderly pattern is called glass. 
  • Rocks. Aggregates of mineral crystals or grains, or masses of natural glass, are called rocks. Geologists recognize three main groups of rocks. (1) Igneous rocks develop when hot molten (liquid) rock cools and freezes solid. (2) Sedimentary rocks form from grains that break off pre-existing rock and become cemented together, or from minerals that precipitate out of a water solution. (3) Metamorphic rocks form when pre-existing rocks change in response to heat and pressure. 
  • Sediment. An accumulation of loose mineral grains (grains that have not stuck together) is called sediment. 
  • Metals. A solid composed of metal atoms (such as iron, aluminium, copper, and tin) is called a metal. An alloy is a mixture containing more than one type of metal atom. 
  • Melts. A melt forms when solid materials become hot and transform into liquid. Molten rock is a type of melt geologists distinguish between magma, which is molten rock beneath the Earth’s surface, and lava, molten rock that has flowed out onto the Earth’s surface. 
  • Volatiles. Materials that easily transform into gas at the relatively low temperatures found at the Earth’s surface are called volatiles. 
The most common minerals in the Earth contain silica (a compound of silicon and oxygen) mixed in varying proportions with other elements. These minerals are called silicate minerals. Not surprisingly, rocks composed of silicate minerals are silicate rocks. Geologists distinguish four classes of igneous silicate rocks based, in essence, on the proportion of silica to iron and magnesium. In order, from greatest to least proportion of silica to iron and magnesium, these classes are felsic (or silicic), intermediate, mafic, and ultramafic. As the proportion of silica in a rock increases, the density (mass per unit volume) decreases. Thus, felsic rocks are less dense than mafic rocks. Many different rock types occur in each class, as will be discussed in detail in Chapters 4 through 7. For now, we introduce the four rock types whose names we need to know for our discussion of the Earth’s layers that follows. These are (1) granite, a felsic rock with large grains; (2) gabbro, a mafic rock with large grains; (3) basalt, a mafic rock with small grains; and (4) peridotite, an ultramafic rock with large grains.

Discovering the Earth’s Internal Layers


People have speculated about what’s inside our planet since ancient times. What is the source of incandescent lavas that spew from volcanoes, of precious gems and metals found in mines, of sparkling mineral waters that bubble from springs, and of the mysterious forces that shake the ground and topple buildings? In ancient Greece and Rome, the subsurface was the underworld, Hades, home of the dead, a region of fire and sulphurous fumes. Perhaps this image was inspired by the molten rock and smoke emitted by the volcanoes of the Mediterranean region. In the 18th and 19th centuries, European writers thought the Earth’s interior resembled a sponge, containing open caverns variously filled with molten rock, water, or air. In fact, in the popular 1864 novel Journey to the Centre of the Earth, by the French author Jules Verne, three explorers hike through interconnected caverns down to the Earth’s centre.
How can we explore the interior for real? We can’t dig or drill down very far. Indeed, the deepest mine penetrates only about 3.5 km beneath the surface of South Africa. And the deepest drill hole probes only 12 km below the surface of northern Russia compared with the 6,371 km radius of the Earth, this hole makes it less than 0.2% of the way to the centre and is nothing more than a pinprick. Our modern image of the Earth’s interior, one made up of distinct layers, is the end product of many discoveries made during the past 200 years.
The first clue that led away from Jules Verne’s sponge image came when researchers successfully measured the mass of the whole Earth, and from this information derived its average density. They found that the average density of our planet far exceeds the density of common rocks found on the surface. Thus, the interior of the Earth must contain denser material than its outermost layer and can’t possibly be full of holes. In fact, the mass of the Earth overall is so great that the planet must contain a large amount of metal. Since the Earth is close to being a sphere, the metal must be concentrated near the centre. Otherwise, centrifugal force due to the spin of the Earth on its axis would pull the equator out, and the planet would become a disk. (To picture why, consider that when you swing a hammer, your hand feels more force if you hold the end of the light wooden shaft, rather than the heavy metal head.) Finally, researchers realized that, though molten rock occasionally oozes out of the interior at volcanoes, the interior must be mostly solid, because if it weren't, the land surface would rise and fall due to tidal forces much more than it does.
An early image of Earth’s internal layers.
Eventually, researchers concluded that the Earth resembled a hard-boiled egg, in that it had three principal layers: a not-so-dense crust (like an eggshell, composed of rocks such as granite, basalt, and gabbro), a denser solid mantle in the middle (the “white,” composed of a then-unknown material), and a very dense core (the “yolk,” composed of an unknown metal) (figure above). Clearly, many questions remained. How thick are the layers? Are the boundaries between layers sharp or gradational? And what exactly are the layers composed of?

Clues from the Study of Earthquakes: Refining the Image

Faulting and earthquakes.
When rock within the outer portion of the Earth suddenly breaks and slips along a fracture called a fault, it generates shock waves (abrupt vibrations), called seismic waves, that travel through the surrounding rock outward from the break. Where these waves cause the surface of the Earth to vibrate, people feel an earthquake, an episode of ground shaking. You can simulate this process, at a small scale, when you break a stick between your hands and feel the snap with your hands (figure above).
In the late 19th century, geologists learned that earthquake energy could travel, in the form of waves, all the way through the Earth’s interior from one side to the other. Geologists immediately realized that the study of earthquake waves travelling through the Earth might provide a tool for exploring the Earth’s insides, much as ultrasound today helps doctors study a patient’s insides. Specifically, laboratory measurements demonstrated that earthquake waves travel at different velocities (speeds) through different materials. Thus, by detecting depths at which velocities suddenly change, geoscientists pinpointed the boundaries between layers and even recognized subtler boundaries within layers. For example, such studies led geoscientists to subdivide the mantle into the upper mantle and lower mantle, and subdivide the core into the inner core and outer core.

Pressure and Temperature Inside the Earth


In order to keep underground tunnels from collapsing under the pressure created by the weight of overlying rock, mining engineers must design sturdy support structures. It is no surprise that deeper tunnels require stronger supports: the downward push from the weight of overlying rock increases with depth, simply because the mass of the overlying rock layer increases with depth. In solid rock, the pressure at a depth of 1 km is about 300 atm. At the Earth’s centre, pressure probably reaches about 3,600,000 atm. Temperature also increases with depth in the Earth. Even on a cool winter’s day, miners who chisel away at gold veins exposed in tunnels 3.5 km below the surface swelter in temperatures of about 53°C (127°F). We refer to the rate of change in temperature with depth as the geothermal gradient. In the upper part of the crust, the geothermal gradient averages between 20°C and 30°C per km. At greater depths, the rate decreases to 10°C per km or less. Thus, 35 km below the surface of a continent, the temperature reaches 400°C to 700°C, and the mantle-core boundary is about 3,500°C. No one has ever directly measured the temperature at the Earth’s centre, but calculations suggest it may exceed 4,700°C, close to the Sun’s surface temperature of 5,500°C.