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Franktown Cave
Franktown Cave is located 25 miles south of Denver, Colorado on the north edge of the Palmer Divide. It is the largest rock shelter documented on the Palmer Divide, which contains artifacts from many prehistoric cultures. Prehistoric hunter-gatherers occupied Franktown Cave intermittently for 8000 years beginning about 6400 B.C. The site held remarkable lithic and ceramic artifacts, but it is better known for its perishable artifacts, including animal hides, wood, fiber and corn. Material goods were produced for their comfort, task-simplification and religious celebration. There is evidence of the site being a campsite or dwelling as recent as AD 1725. Geography Franktown Cave is a rock shelter above Willow Creek, a tributary of Cherry Creek (Colorado), Cherry Creek that flows into the South Platte River at Denver, Colorado, 25 miles to the north. It is more than in elevation. Situated on Palmer Divide, which separates the South Platte River basin from the Arkansas River basin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franktown, Colorado
Franktown is an Unincorporated area, unincorporated town, a post office, and a Census-designated place, census-designated place (CDP) located in and governed by Douglas County, Colorado, Douglas County, Colorado, United States. The CDP is a part of the Denver–Aurora–Lakewood, CO Metropolitan Statistical Area. The Franktown post office has the ZIP Code 80116. At the United States Census 2010, the population of the Franktown CDP was 395, while the population of the 80116 ZIP Code Tabulation Area was 3,942 including adjacent areas. Douglas County governs the unincorporated town. History Franktown is named for Hon. J. Frank Gardner, an early resident. Franktown was the first county seat of Douglas County, Colorado, Douglas County, serving in this role from 1861 until 1863. James Frank Gardner, a would-be gold miner who built a squatter's cabin four miles north of here in 1859. A popular rest stop on the busy Jimmy's Camp, Colorado, Jimmy Camp Trail (which followed Cherry Creek int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arkose
Arkose () or arkosic sandstone is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is commonly the dominant mineral component, and some mica is often present. Apart from the mineral content, rock fragments may also be a significant component. Arkose usually contains small amounts of calcite cement, which causes it to effervesce (fizz) slightly in dilute hydrochloric acid; sometimes the cement also contains iron oxide. Arkose is typically grey to reddish in colour. The sand grains making up an arkose may range from fine to very coarse, but tend toward the coarser end of the scale. Fossils are rare in arkose, due to the depositional processes that form it, although bedding is frequently visible. Arkose is generally formed from the weathering of feldspar-rich igneous or metamorphic, most commonly granitic, rocks, which are p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quercus Gambelii
''Quercus gambelii'', with the common name Gambel oak, is a deciduous small tree or large shrub that is widespread in the foothills and lower mountains of western North America. It is also regionally called scrub oak, oak brush, and white oak. The common and scientific names, Gambel oak and ''Quercus gambelii'', were named after the American naturalists, naturalist William Gambel (1821–1849). Description ''Quercus gambelii'' trees differ in size from one location to another. The average mature height is from , but occasionally reaches heights of in some locations. Dwarf stands of plants under tall are common in marginal areas where heavy browsing occurs. The largest trees are found in the southern range of the species along streams. These trees reach up to 100 feet tall. The champion tree is in Arizona at tall. Although the wood is hard and dense, its branches are irregular and crooked, making them flexible enough to bend without breaking when covered with heavy sno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
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] |
List Of Largest Volcanic Eruptions
In a volcanic eruption, lava, volcanic bombs and ash, and various gases are expelled from a volcanic vent and fissure. While many eruptions only pose dangers to the immediately surrounding area, Earth's largest eruptions can have a major regional or even global impact, with some affecting the climate and contributing to mass extinctions. Volcanic eruptions can generally be characterized as either explosive eruptions, sudden ejections of rock and ash, or effusive eruptions, relatively gentle outpourings of lava. A separate list is given below for each type. There have probably been many such eruptions during Earth's history beyond those shown in these lists. However erosion and plate tectonics have taken their toll, and many eruptions have not left enough evidence for geologists to establish their size. Even for the eruptions listed here, estimates of the volume erupted can be subject to considerable uncertainty. Explosive eruptions In explosive eruptions, the eruption of magma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcrystalline
A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination. There is little agreement on the range of crystal sizes that should be regarded as microcrystalline, but the extreme range of values suggested is 1 to 200 microns. See also * Macrocrystalline * Nanocrystalline silicon * Microcrystalline cellulose * Microcrystalline wax * Protocrystalline * Rock microstructure Rock microstructure includes the texture and small-scale structures of a rock. The words ''texture'' and ''microstructure'' are interchangeable, with the latter preferred in modern geological literature. However, ''texture'' is still acceptable b ... References Mineralogy concepts Petrology concepts {{Petrology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biface
A hand axe (or handaxe or Acheulean hand axe) is a Prehistory, prehistoric stone tool with two faces that is the longest-used tool in human history, yet there is no academic consensus on what they were used for. It is made from stone, usually flint or chert that has been "reduced" and shaped from a larger piece by knapping, or hitting against another stone. They are characteristic of the lower Acheulean and middle Palaeolithic (Mousterian) periods, roughly 1.6 million years ago to about 100,000 years ago, and used by ''Homo erectus'' and other early humans, but rarely by ''Homo sapiens''. Their technical name (biface) comes from the fact that the archetypical model is a generally bifacial (with two wide sides or faces) and almond-shaped (amygdaloidal) lithic flake. Hand axes tend to be Symmetry, symmetrical along their longitudinal Symmetry axis, axis and formed by pressure or percussion. The most common hand axes have a pointed end and rounded base, which gives them their char ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Projectile Point
In North American archaeological terminology, a projectile point is an object that was hafted to a weapon that was capable of being thrown or projected, such as a javelin, dart, or arrow. They are thus different from weapons presumed to have been kept in the hand, such as knives, spears, axes, hammers, and maces. Stone tools, including projectile points, can survive for long periods, were often lost or discarded, and are relatively plentiful, especially at archaeological sites. They provide useful clues to the human past, including prehistoric trade. A distinctive form of point, identified though lithic analysis of the way it was made, is often a key diagnostic factor in identifying an archaeological industry or culture. Scientific techniques exist to track the specific kinds of rock or minerals that were used to make stone tools in various regions back to their original sources. As well as stone, projectile points were also made of worked wood, bone, antler, horn, or ivory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by Chicxulub impact, an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. In the Pal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrified Wood
Petrified wood, also known as petrified tree (from Ancient Greek meaning 'rock' or 'stone'; literally 'wood turned into stone'), is the name given to a special type of ''fossilized wood'', the fossilized remains of terrestrial vegetation. ''Petrifaction'' is the result of a tree or tree-like plants having been replaced by stone via a mineralization process that often includes permineralization and replacement. The organic materials making up cell walls have been replicated with minerals (mostly silica in the form of opal, chalcedony, or quartz). In some instances, the original structure of the stem tissue may be partially retained. Unlike other plant fossils, which are typically impressions or compressions, petrified wood is a three-dimensional representation of the original organic material. The petrifaction process occurs underground, when wood becomes buried in water-saturated sediment or volcanic ash. The presence of water reduces the availability of oxygen which inhibits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalcedony
Chalcedony ( , or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide). Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black. The color of chalcedony sold commercially is often enhanced by dyeing or heating. The name ''chalcedony'' comes from the Latin ''chalcedonius'' (alternatively spelled ''calchedonius'') and is probably derived from the town of Chalcedon in Turkey. The name appears in Pliny the Elder's ''Naturalis Historia'' as a term for a translucent kind of jaspis. Another reference to a gem by the name of ''khalkedon'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
