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Espinaso Formation
The Espinaso Formation is a geologic formation in New Mexico. It has a radiometric age of 34.6 to 26.9 million years, corresponding to the late Eocene through Oligocene epochs. Description The Espinaso Formation is principally debris flows and lahars from the Ortiz porphyry belt, with some interbedded lava flows and tuff beds. The upper part of the formation is dominated by upward-fining sequences, where sediments are coarser near the base of the sequence and finer towards the top. This suggests waning volcanic activity and decreasing topographic relief. The formation intertongues with the underlying Galisteo Formation but unconformably underlies the Tanos Formation of the Santa Fe Group. Radiometric dating gives an age range of 34.3 +/-0.8 million years ( Ma) near the base of the formation, 34.6 +/-0.7 Ma near the middle, and 26.9 +/-0.6 my near the top. A basalt flow at the base of the overlying Tanos Formation has an age of 25.1 +/-0.6 Ma. The formation crops out in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
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 (geology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Flows
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementation (geology)
Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. The new pore-filling minerals forms "bridges" between original sediment grains, thereby binding them together. In this way, ''sand'' becomes sandstone, and ''gravel'' becomes conglomerate or breccia. Cementation occurs as part of the diagenesis or lithification of sediments. Cementation occurs primarily below the water table regardless of sedimentary grain sizes present. Large volumes of pore water must pass through sediment pores for new mineral cements to crystallize and so millions of years are generally required to complete the cementation process. Common mineral cements include calcite, quartz, and silica phases like cristobalite, iron oxides, and clay minerals; other mineral cements also occur. Cementation is continuous in the groundwater zone, so much so that the term "zone of cementation" is sometimes used interchangeably. Cementati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hogback (geology)
In geology and geomorphology, a hogback or hog's back is a long, narrow ridge or a series of hills with a narrow crest and steep slopes of nearly equal inclination on both flanks. Typically, the term is restricted to a ridge created by the differential erosion of outcropping, steeply dipping (greater than 30–40°), homoclinal, and typically sedimentary strata. One side of a hogback (its backslope) consists of the surface (bedding plane) of a steeply dipping rock stratum called a dip slope. The other side (its escarpment, frontslope or "scarp slope") is an erosion face that cuts through the dipping strata that comprises the hogback.Huggett, JR (2011) ''Fundamentals of Geomorphology,'' 3rd ed., Routledge, New York. 516 pp. Cotton, CA (1952) ''Geomorphology An Introduction to the Study of Landforms, 6th ed.'' John Wiley and Sons, New York. 505 pp.Fairbridge, RW (1968) ''Hogback and Flatiron.'' In RW Fairbridge, ed., pp. 524-525, ''The Encyclopedia of Geomorphology'' (Encyclopedia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slot Canyon
A slot canyon is a long, narrow channel or drainageway with sheer rock walls that are typically eroded into either sandstone or other sedimentary rock. A slot canyon has depth-to-width ratios that typically exceed 10:1 over most of its length and can approach 100:1. The term is especially used in the semiarid southwestern United States and particularly the Colorado Plateau. Slot canyons are subject to flash flooding and commonly contain unique ecological communities that are distinct from the adjacent, drier uplands. Some slot canyons can measure less than across at the top but drop more than to the floor of the canyon. Many slot canyons are formed in sandstone and limestone rock, although slot canyons in other rock types such as granite and basalt are possible. Even in sandstone and limestone, only a very small number of streams will form slot canyons due to a combination of the particular characteristics of the rock and regional rainfall. Around the world Slot canyons are foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Section
A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. Also it can be defined as "The particular sequence of strata chosen as standard of reference of a layered stratigraphic unit." When a stratigraphic unit is nowhere fully exposed, the original type section may be supplemented with reference sections covering the full thickness of the unit. A reference section may also be defined when the original type section is poorly exposed, or for historical units which were designated without specifying a type section according to more modern standards. See also * Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
La Cienega, New Mexico
La Cienega is a census-designated place (CDP) in Santa Fe County, New Mexico, United States. It is part of the Santa Fe, New Mexico, metropolitan statistical area. The population was 3,007 at the 2000 census. La Cienega is located on the site of a Keres pueblo that took part in the 1680 Pueblo Revolt. Geography La Cienega is located at (35.592537, -106.108947). According to the United States Census Bureau, the CDP has a total area of , all land. The South End of the Rockies Historical Marker, marking the southern terminus of the Rocky Mountains, is about three miles west of La Cienega. Wetlands The name La Cienega refers to an important feature, a cienega (spring and associated marsh) that supplies water to El Rancho de las Golondrinas and the Santa Fe River Canyon at the foot of the Caja del Rio. The cienega itself is managed by the Santa Fe Botanical Garden as the Leonora Curtin Wetland Preserve. La Cienega is an Area of Critical Environmental Concern and has been a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galisteo Basin
The Galisteo Basin is a surface basin and a closely related groundwater basin in north-central New Mexico. Its primary watercourse is the Galisteo River or Galisteo Creek, a perennial stream, for part of its course, that flows from the eastern highlands down into the Rio Grande about three miles above the Santo Domingo Pueblo. The Galisteo basin covers approximately 467,200 acres and runs from San Miguel County in the east, across Santa Fe County, and into Sandoval County at its westernmost point, the Rio Grande. Northeast of Galisteo Basin rise the Sangre de Cristo Mountains and to the southwest lie the Sandia Mountains. Because of its location lying between mountain ranges and connecting the upper Rio Grande Valley with the Great Plains, the Galisteo Basin was used as a trade route by prehistoric and historic indigenous and later also by the Spanish explorers. Geography The Galisteo Basin drains the southern Sangre de Cristo Mountains, shares its northern drainage div ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hagan, New Mexico
Hagan is a ghost town in Sandoval County, New Mexico, United States, about southeast of San Felipe Pueblo. History In 1902 the New Mexico Fuel and Iron Company was established to develop coal mines in the locality. The name "Hagan" was chosen for the site in 1904, named after a local official of the AT&SF Railroad, no doubt to encourage the extension of a railroad spur to serve the mines. Initially, coal was hauled by wagon to the railroad main line at San Felipe. Work on the spur was begun in 1908 but was suspended within months, stalling development of the community of about 60 residents for a decade. In 1919 a "gentleman entrepreneur", Jean Justin DePraslin of New Orleans, convinced investors to put up nearly $450,000 to develop the Hagan Coal Mine, including housing, mine buildings and a power plant. A further $300,000 was raised for a new railroad, the Rio Grande Eastern, and the line was completed in May 1924. As well as the coal, the railroad hauled brick and tile from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Million Years
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). Together they make a reference system, one to a quantity, the other to a particular place in a year numbering system that is ''time before the present''. Myr is deprecated in geology, but in astronomy ''Myr'' is standard. Where "myr" ''is'' seen in geology it is usually "Myr" (a unit of mega-years). In astronomy it is usually "Myr" (Million years). Debate In geology a debate remains open concerning the use of ''Myr'' (duration) plus ''Ma'' (million years ago) versus using only the term ''Ma''. In either case the term '' Ma'' is used in geology literature conforming to ISO 31-1 (now ISO 80000-3) and NIST 811 recommended practices. Traditional style geology literature is written The "ago" is implied, so that any such year number "X Ma" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Santa Fe Group (geology)
The Santa Fe Group is a group of geologic formations in New Mexico and Colorado. It contains fossils characteristic of the Oligocene through Pleistocene epochs. The group consists of basin-filling sedimentary and volcanic rocks of the Rio Grande rift, and contains important regional aquifers. Description The Santa Fe Group is widely defined as basin-filling sedimentary and volcanic rocks of the Rio Grande rift. These range in age from late Oligocene to Pleistocene. The oldest formations in the group correspond to the earliest structural deformation associated with rifting. Geologic uplift of the region around the rift has ended deposition, and erosion in the Rio Grande river system has exposed many of the beds deposited earlier, often spectacularly, as in the badlands north of Santa Fe. The formations in the group are divided into lower and upper sections. The lower Santa Fe Group was deposited in bolsons (closed arid basins) where streams drained into intermittent play ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
