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Laguna Brava Formation
Laguna Brava Formation ( es, Formación Laguna Brava), formerly referred to as Santo Domingo Formation, is a Late Eocene (Tinguirirican in the SALMA classification) sedimentary formation located in the Argentine Northwest.Quebrada de Santa Domingo at .org The formation contains beds with described as '' Gruipeda domingue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossiliferous Stratigraphic Units Of South America
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacustrine Deposits
Lacustrine deposits are sedimentary rock formations which formed in the bottom of ancient lakes. A common characteristic of lacustrine deposits is that a river or stream channel has carried sediment into the basin. Lacustrine deposits form in all lake types including rift graben lakes, oxbow lakes, glacial lakes, and crater lakes. Lacustrine environments, like seas, are large bodies of water. They share similar sedimentary deposits which are mainly composed of low-energy particle sizes. Lacustrine deposits are typically very well sorted with highly laminated beds of silts, clays, and occasionally carbonates. In regards to geologic time, lakes are temporary and once they no longer receive water, they dry up and leave a formation. Lake types Lacustrine deposits can form in every variety of basins found in nature. How each basin originates is where the distinction between lacustrine deposit types stem. Rift graben lakes are formed from crustal stretching also known as rifting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial Deposits
In geography and geology, fluvial processes are associated with rivers and streams and the Deposition (geology), deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes Fluvial processes include the sediment transport, motion of sediment and erosion or deposition (geology), deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed. If the Cohesion (geology), cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. In addition, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed (abrasion (geology), abrasion). At the same time the fragments themselves are ground down, becoming smaller ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff Formations
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone Formations
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topography, topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porosity, porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priabonian Stage
The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage of the Oligocene. Stratigraphic definition The Priabonian Stage was introduced in scientific literature by Ernest Munier-Chalmas and Albert de Lapparent in 1893. The stage is named after the small hamlet of Priabona in the community of Monte di Malo, in the Veneto region of northern Italy. The base of the Priabonian Stage is at the first appearance of calcareous nannoplankton species ''Chiasmolithus oamaruensis'' (which forms the base of nanoplankton biozone NP18). An official GSSP was ratified in 2020, and was placed in the Alano di Piave section in Alano di Piave, Belluno, Italy. The top of the Priabonian Stage (the base of the Rupelian Stage and Oligocene Series) is at the extinction of foram genus ''Hantkenina''. Sometimes local ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleogene Argentina
The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya) to the beginning of the Neogene Period Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon. The earlier term Tertiary Period was used to define the span of time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognised as a formal stratigraphic term, 'Tertiary' is still widely found in earth science literature and remains in informal use. Paleogene is often abbreviated "Pg" (but the United States Geological Survey uses the abbreviation PE for the Paleogene on the Survey's geologic maps). During the Paleogene, mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction event that ended the preceding Cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene Series Of South America
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Formations Of Argentina
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes of Earth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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