Relative dating

Methods for relative dating were developed when geology first emerged as a natural science. The following principles are still used by geologists today as a means of providing information about geological history and the timing of geological events.

absolute dating

Geologists also use methods to determine the absolute age of rock samples and geological events. These dates are useful on their own and can also be used in conjunction with relative dating methods or to calibrate relative methods.[28]​.

At the turn of the century, the advancement of geological science was facilitated by the ability to obtain precise absolute dates of geological events using radioactive isotopes and other methods. This changed the understanding of geological time. Previously, geologists could only use fossils and stratigraphic correlation to date sections of rock to each other. With isotopic dates, it was possible to assign absolute ages to rock units, and these absolute dates could be applied to fossil sequences in which datable material was present, converting old relative ages into new absolute ages.

For many geological applications, isotope ratios of radioactive elements are measured in minerals giving the amount of time that has passed since a rock passed its particular closure temperature, the point at which different radiometric isotopes stop diffusing in and out of the crystal lattice.[29][30]These are used in geochronological and thermochronological studies. Common methods include uranium-lead dating, potassium-argon dating, argon-argon dating, and uranium-thorium dating. These methods are used for a variety of applications. Dating of lava and volcanic ash layers found within a stratigraphic sequence can provide absolute age data for sedimentary rock units that do not contain radioactive isotopes and calibrate relative dating techniques. These methods can also be used to determine the emplacement ages of plutons. Thermochemical techniques can be used to determine temperature profiles within the crust, the elevation of mountain ranges, and paleo-topography.

Fractionation of lanthanide series elements is used to calculate ages since rocks were removed from the mantle.

Other methods are used for more recent events. Optically stimulated luminescence and cosmogenic radionuclide dating are used to date surfaces and/or erosion rates. Dendrochronology can also be used for landscape dating. Radiocarbon dating is used for geologically young materials containing organic carbon.

plate tectonics

In the 1960s it was discovered that the Earth's lithosphere, which includes the crust "Crust (geology)") and the rigid upper part of the upper mantle, is separated into tectonic plates that move through the deformable plastic solid upper mantle "Plasticity (mechanics of solids)"), which is called the asthenosphere. This theory is supported by several types of observations, such as seafloor spreading[31][32]​ and the global distribution of mountainous terrain and seismicity.

There is an intimate coupling between plate motion at the surface and mantle convection (i.e., heat transfer caused by the slow movement of ductile rock in the mantle). Thus, oceanic plates and adjacent mantle convection currents always move in the same direction, because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convective mantle. This coupling between the rigid plates moving on the Earth's surface and the convective mantle is called plate tectonics.

The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geological features are explained as plate boundaries.[33]​.

For example:.

Transform edges, such as the San Andreas fault system, gave rise to powerful widespread earthquakes. Plate tectonics has also provided a mechanism for Alfred Wegener's theory of continental drift,[34] in which continents move across the Earth's surface over geological time. They also provided a driving force for crustal deformation, and a new setting for observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves above the convective mantle.

Earth Structure

Advances in seismology, numerical modeling and mineralogy and crystallography at high temperatures and pressures allow us to understand the internal composition and structure of the Earth.

Seismologists can use the arrival times of seismic waves to obtain images of the Earth's interior. The first advances in this field showed the existence of a liquid outer core (where shear waves" could not propagate) and a solid, dense inner core. These advances led to the development of a stratified model of the Earth, with a crust "Crust (geology)") and a lithosphere on top, the mantle "Mantle (geology)") below (separated in its interior by seismic discontinuities at 410 and 660 kilometers), and the outer core and the inner core below. More recently, seismologists have been able to create detailed images of wave speeds inside the Earth, in the same way that a doctor images a body in a tomography scan. These images have allowed a much more detailed view of the Earth's interior and have replaced the simplified layer model with a much more dynamic model.

Mineralogists have been able to use pressure and temperature data from seismic and modeling studies along with knowledge of the Earth's elemental composition to reproduce these conditions in experimental settings and measure changes in crystal structure. These studies explain the chemical changes associated with the main seismic discontinuities of the mantle and show the crystalline structures expected in the Earth's inner core.

Regional geology

Regional geology") is the branch of geology that studies the geological configuration of each continent, country, region or specific areas of the Earth.

Geology includes different sciences or disciplines, which make up university or professional educational training plans. Due to the great diversity of disciplines or geological sciences, these are grouped into different independent teaching units, where a better modular organization of the teaching and research of Geology on the different sciences it comprises is carried out. One of the general structures in which these departments are composed is:

A geologist is a specialist and professional in the study, observation or experimentation related to the Earth, its composition, structure, dynamics, origin and evolution. In your professional work you must apply the principles of geoethics.

A geologist stands out for having the following skills:

Relative dating

Methods for relative dating were developed when geology first emerged as a natural science. The following principles are still used by geologists today as a means of providing information about geological history and the timing of geological events.

absolute dating

Geologists also use methods to determine the absolute age of rock samples and geological events. These dates are useful on their own and can also be used in conjunction with relative dating methods or to calibrate relative methods.[28]​.

At the turn of the century, the advancement of geological science was facilitated by the ability to obtain precise absolute dates of geological events using radioactive isotopes and other methods. This changed the understanding of geological time. Previously, geologists could only use fossils and stratigraphic correlation to date sections of rock to each other. With isotopic dates, it was possible to assign absolute ages to rock units, and these absolute dates could be applied to fossil sequences in which datable material was present, converting old relative ages into new absolute ages.

For many geological applications, isotope ratios of radioactive elements are measured in minerals giving the amount of time that has passed since a rock passed its particular closure temperature, the point at which different radiometric isotopes stop diffusing in and out of the crystal lattice.[29][30]These are used in geochronological and thermochronological studies. Common methods include uranium-lead dating, potassium-argon dating, argon-argon dating, and uranium-thorium dating. These methods are used for a variety of applications. Dating of lava and volcanic ash layers found within a stratigraphic sequence can provide absolute age data for sedimentary rock units that do not contain radioactive isotopes and calibrate relative dating techniques. These methods can also be used to determine the emplacement ages of plutons. Thermochemical techniques can be used to determine temperature profiles within the crust, the elevation of mountain ranges, and paleo-topography.

Fractionation of lanthanide series elements is used to calculate ages since rocks were removed from the mantle.

Other methods are used for more recent events. Optically stimulated luminescence and cosmogenic radionuclide dating are used to date surfaces and/or erosion rates. Dendrochronology can also be used for landscape dating. Radiocarbon dating is used for geologically young materials containing organic carbon.

plate tectonics

In the 1960s it was discovered that the Earth's lithosphere, which includes the crust "Crust (geology)") and the rigid upper part of the upper mantle, is separated into tectonic plates that move through the deformable plastic solid upper mantle "Plasticity (mechanics of solids)"), which is called the asthenosphere. This theory is supported by several types of observations, such as seafloor spreading[31][32]​ and the global distribution of mountainous terrain and seismicity.

There is an intimate coupling between plate motion at the surface and mantle convection (i.e., heat transfer caused by the slow movement of ductile rock in the mantle). Thus, oceanic plates and adjacent mantle convection currents always move in the same direction, because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convective mantle. This coupling between the rigid plates moving on the Earth's surface and the convective mantle is called plate tectonics.

The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geological features are explained as plate boundaries.[33]​.

For example:.

Transform edges, such as the San Andreas fault system, gave rise to powerful widespread earthquakes. Plate tectonics has also provided a mechanism for Alfred Wegener's theory of continental drift,[34] in which continents move across the Earth's surface over geological time. They also provided a driving force for crustal deformation, and a new setting for observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves above the convective mantle.

Earth Structure

Advances in seismology, numerical modeling and mineralogy and crystallography at high temperatures and pressures allow us to understand the internal composition and structure of the Earth.

Seismologists can use the arrival times of seismic waves to obtain images of the Earth's interior. The first advances in this field showed the existence of a liquid outer core (where shear waves" could not propagate) and a solid, dense inner core. These advances led to the development of a stratified model of the Earth, with a crust "Crust (geology)") and a lithosphere on top, the mantle "Mantle (geology)") below (separated in its interior by seismic discontinuities at 410 and 660 kilometers), and the outer core and the inner core below. More recently, seismologists have been able to create detailed images of wave speeds inside the Earth, in the same way that a doctor images a body in a tomography scan. These images have allowed a much more detailed view of the Earth's interior and have replaced the simplified layer model with a much more dynamic model.

Mineralogists have been able to use pressure and temperature data from seismic and modeling studies along with knowledge of the Earth's elemental composition to reproduce these conditions in experimental settings and measure changes in crystal structure. These studies explain the chemical changes associated with the main seismic discontinuities of the mantle and show the crystalline structures expected in the Earth's inner core.

Regional geology

Regional geology") is the branch of geology that studies the geological configuration of each continent, country, region or specific areas of the Earth.

Geology includes different sciences or disciplines, which make up university or professional educational training plans. Due to the great diversity of disciplines or geological sciences, these are grouped into different independent teaching units, where a better modular organization of the teaching and research of Geology on the different sciences it comprises is carried out. One of the general structures in which these departments are composed is:

A geologist is a specialist and professional in the study, observation or experimentation related to the Earth, its composition, structure, dynamics, origin and evolution. In your professional work you must apply the principles of geoethics.

A geologist stands out for having the following skills: