Transgression: In geology, the term transgression is the formation of a specific sequence of sedimentary and metamorphic layers, that are the result of ocean water advancing onto land. To illustrate, when transgression occurs over millions of years, geologists find a layer of sand, overlain by shale, and overlain again by limestone. The opposite of transgression is regression.
Rock Stratigraphic Unit In the field of geology, a rock stratigraphic unit, or a lithostratigraphic unit, is a geologic formation that is identifiable by a specific lithology, as well as a consistent stratigraphic position. For example, the Monterey Formation is a rock stratigraphic unit, as it tends to consistently comprise the same gravel and sand…
Mineral Definition A mineral is defined as an inorganic element, compound, or substance that naturally develops with an organized internal structure and/or crystal form over time. Minerals are also distinguishable by their chemical composition and physical properties, as determined in laboratories by geologists. Typical earth minerals found in most igneous, metamorphic, and sedimentary rocks are…
Epicenter Epicenter: In the seismology branch of geology, an epicenter of an earthquake is the point on Earth’s surface that is directly above the focus (or hypocenter). It is the ground surface location overlying where an earthquake rupture originates within a dip-slip fault or strike-slip fault. Shortly after an earthquake, United States Geological Survey (USGS)…
Consistency The term “Consistency” in the fields of engineering geology and geotechnical engineering means the degree of adhesion between soil particles within a sample, that are observed to resist deformation or rupture.
Rigidity Definition Rigidity – In geotechnical engineering and engineering geology, rigidity represents the ratio of the shear stress and the amount of angular rotation that it produces, within a rock sample.
Troposphere Troposphere: The troposphere of a terrestrial planet is the lowest member of the atmosphere. On Earth, the troposphere starts atop the ground surface and terminates roughly 10 kilometers above mean sea level. In fact, geologists understand that most of the Earth’s water vapor (clouds) exists in the troposphere. And the next member of the…
