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Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems.
Mount Katahdin is the highest mountain in the U.S. state of Maine at 5,269 feet (1,606 m). Named Katahdin, which means "Great Mountain", by the Penobscot Native Americans, it is within Northeast Piscataquis, Piscataquis County, and is the centerpiece of Baxter State Park. It is a steep, tall massif formed from a granite intrusion weathered to the surface. The flora and fauna on the mountain are typical of those found in northern New England.
Glacial landforms are landforms created by the action of glaciers. Most of today's glacial landforms were created by the movement of large ice sheets during the Quaternary glaciations. Some areas, like Fennoscandia and the southern Andes, have extensive occurrences of glacial landforms; other areas, such as the Sahara, display rare and very old fossil glacial landforms.
Striations means a series of ridges, furrows or linear marks, and is used in several ways:
Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them with moving glaciers. They also noted that if they were visible today that the glaciers must also be receding.
Boulder clay is an unsorted agglomeration of clastic sediment that is unstratified and structureless and contains gravel of various sizes, shapes, and compositions distributed at random in a fine-grained matrix. The fine-grained matrix consists of stiff, hard, pulverized clay or rock flour. Boulder clay is also known as either known as drift clay; till; unstratified drift, geschiebelehm (German); argile á blocaux (French); and keileem (Dutch).
Plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the weathering and erosion of pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier". As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock. The freezing and thawing action of the ice enlarges, widens, or causes further cracks in the bedrock as it changes volume across the ice/water phase transition, gradually loosening the rock between the joints. This produces large pieces of rock called joint blocks. Eventually these joint blocks come loose and become trapped in the glacier.
Trachyonychia is a condition characterized by rough accentuated linear ridges on the nails of the fingers and toes. When the condition occurs on all the twenty nails of the fingers and toes, it is known as twenty-nail dystrophy, most evident in childhood, favoring males.
Banji is an extinct genus of oviraptorid dinosaur that lived approximately 66 million years ago during the later part of the Cretaceous Period in what is now China. It was a small, lightly-built, ground-dwelling, bipedal carnivore, that was an estimated 65 cm (2.1 ft) long, as a juvenile.
Rat Rock, also known as Umpire Rock, is an outcrop of Manhattan schist which protrudes from the bedrock in Central Park, Manhattan, New York City. It is named after the rats that used to swarm there at night. It is located near the southwest corner of the park, south of the Heckscher Ballfields near the alignments of 62nd Street and Seventh Avenue. It measures 55 feet (17 m) wide and 15 feet (4.6 m) tall with different east, west, and north faces, each of which present differing climbing challenges. The rock has striations caused by glaciation.
In geology, a striation is a groove, created by a geological process, on the surface of a rock or a mineral.
Striation Valley is a valley trending south-east towards George VI Sound, lying immediately north of Jupiter Glacier, near the east coast of Alexander Island, Antarctica. The valley was first surveyed by a field party from the Department of Geography at the University of Aberdeen, with British Antarctic Survey support, in 1978–79. The name derives from glacial striations found on rocks in the valley. The site lies within Antarctic Specially Protected Area (ASPA) No.147. In 2001, a continuous stand of approximately 1600 m 2 of Antarctic bryophyte vegetation was recorded on moist slopes in lower Striation Valley.
The Exoschizonidae are a family in the phylum Apicomplexa.
Exoschizon is a genus in the phylum Apicomplexa.
Amanita pachycolea, commonly known as the western grisette or the Stuntz's great ringless amanita, is a species of agaric fungus in the family Amanitaceae. It was recognized as a distinct species by mycologist Daniel Elliot Stuntz, and published in 1982 by Harry Delbert Thiers. Found in western North America, it associates with conifers in coniferous and mixed forests. Amanita pachycolea is classified in Amanita section Vaginatae, which includes species with conspicuous radial striations on the cap, inamyloid spores, and the absence of a ring on the stipe. The mushroom is edible, but not recommended due to possible confusion with toxic Amanita species.
Cyrtocycloceras is a genus of orthocerids from the Middle Silurian of Europe included in the Paraphragmitidae.
Forensic firearm examination is the forensic process of examining the characteristics of firearms or bullets left behind at a crime scene. Specialists in this field try to link bullets to weapons and weapons to individuals. They can raise and record obliterated serial numbers in an attempt to find the registered owner of a weapon and look for fingerprints on a weapon and cartridges.
Striations are marks produced on the fracture surface that show the incremental growth of a fatigue crack. A striation marks the position of the crack tip at the time it was made. The term striation generally refers to ductile striations which are rounded bands on the fracture surface separated by depressions or fissures and can have the same appearance on both sides of the mating surfaces of the fatigue crack. Although some research has suggested that many loading cycles are required to form a single striation, it is now generally thought that each striation is the result of a single loading cycle.
Gyrosigma is a genus of diatoms belonging to the family Pleurosigmataceae.
Tateana, and more specifically Tateana inflata, is a very small, discus-like Ediacaran fossil. Its largest diameter is 6.4 mm long and it is radially symmetrical. It has very defined and thin radial striations. The main body seemed to be the main portion of the fossil, not showing signs of any limbs or appendages. Tateana has a central zone to where all the radial striations meet into the middle. The striations do not branch off of a main path and there are about 100 of them on the body.
References
- Walter c. Sweet, 1964. Nautiloidea- Orthocerida. Treatise on Invertebrate Paleontology, Part K. Geologica Society of America.
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