Vitosha, the ancient Scomius or Scombrus, is a mountain massif, on the outskirts of Sofia, the capital of Bulgaria. Vitosha is one of the symbols of Sofia and the closest site for hiking and skiing. Convenient bus lines and rope ways render the mountain accessible. Vitosha has the outlines of an enormous dome; the territory of the mountain includes Vitosha nature park that encompasses the best known and most visited parts. The foothills of Vitosha shelter resort quarters of Sofia. Vitosha is the oldest nature park in the Balkans; the mountain emerged as a result of volcanic activity and has been subsequently shaped by the slow folding of the granite rock layers and a series of gradual uplifts of the area. It appears dome shaped at first sight, but the mountain, 19 km long by 17 km wide consists of concentric denudational plateaus rising in tiers one above the other. Vitosha is separated into four main parts; this is the highest point of the mountain at 2290 m and is one of 10 peaks of Vitosha over 2000 m in height.
Bulgaria's longest cave – Duhlata, with a total length of 18,200 m, is situated in Vitosha in the karstic region near the village of Bosnek. Since the ancient times of the Thracians a large population has always existed at the base of Vitosha. For the last four thousand years the economy of this large settlement has always been connected, in one way or another, with the neighboring mountain; the name Vitosha comes from the two-peaked, twin ridge mountain, which rises above the Sofia field and has acquired its present shape in stages over many millennia. A meteorological station was built at the top in 1935, is still operating; the station serves as a rest shelter for hikers and is the headquarters for the mountain rescue team. Historical documents show that several centuries ago Vitosha mountain was still covered by the remains of the inaccessible "Great Bulgarian Forest". Today, the natural coniferous forests of Vitosha remain only in the reserve Bistrishko Branishte and around Zlatnite Mostove.
The Golden Bridges is a stone river consisting of a ribbon of huge boulders running down the mountainside. This scenic spot is located along the Vladayska River in an area of mixed deciduous and evergreen forest. However, this is only one of the stone rivers found in Vitosha and they were once the moraines of ancient glaciers, their further formation occurred due to the spherical erosion of the sienite rocks and their gradual movement to down stream valleys by the forces of gravity and moving water. At a time when nature conservation ideas were a long way from the present understanding, some enlightened noblemen took the first step in 1934 by declaring 66 km² of Vitosha a nature park, hence Vitosha became the first park of this kind in the Balkans. During the following year, some of the early Bulgarian reserves, Bistrishko Branishte and Torfeno Branishte, were designated within its boundaries; the park boundaries fluctuated over many years and today it encompasses the entire mountain. Due to a great variability in elevation, a rich diversity of climates and fauna can be found within the park.
Research has revealed that on the comparatively small area of the mountain there are 1,500 species of higher plants, 500 species of fungi, 500 species of algae, 326 species of mosses, 200 species of lichens. Among them 31 species are Balkan endemics and 52 species are included in the Red Book of Bulgaria; the forests are made up of Norway Spruce and Bulgarian Fir, with some Macedonian Pine, Scots Pine, at the tree-line, Mountain Pine, mixed deciduous forest at lower altitudes beech, birch and alder. Regarding the herbaceous plants, well established populations of Veratrum album are present in the mountain so as other species called'lilies'. There are Orchids as the East European green-winged orchid that grows in the higher parts. Lungwort is another widespread herbaceous plant in Vitosha and it develops in dank sites under the shade of the forest. Vitosha Saddle, Rezen Knoll, Komini Peak, Kikish Crag on Livingston Island in the South Shetland Islands, Antarctica are named for Mount Vitosha, for the Vitosha peaks of Malak Rezen and Golyam Rezen, Kominite Peak, Kikish site.
Vitosha is the name of: Radio Vitosha Vitosha Boulevard - a popular main street in Sofia. Stone rivers Bistrishko Branishte Torfeno Branishte Aleko Etosha National Park - National Park in Namibia with somewhat similar name but with different ecosystem. Photo Gallery Mountain Vitosha Gallery Nature Park Vitosha Web Site Mountain & Ski resort Vitosha - info, properties The Vitosha mountain - virtual tour Hiking in Vitosha Mountains History of the park, travelling information, photographs Vast Image Gallery of Vitosha
Granite is a common type of felsic intrusive igneous rock, granular and phaneritic in texture. Granites can be predominantly white, pink, or gray depending on their mineralogy; the word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Speaking, granite is an igneous rock with between 20% and 60% quartz by volume, at least 35% of the total feldspar consisting of alkali feldspar, although the term "granite" is used to refer to a wider range of coarse-grained igneous rocks containing quartz and feldspar; the term "granitic" means granite-like and is applied to granite and a group of intrusive igneous rocks with similar textures and slight variations in composition and origin. These rocks consist of feldspar, quartz and amphibole minerals, which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole peppering the lighter color minerals; some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic.
A granitic rock with a porphyritic texture is known as a granite porphyry. Granitoid is a descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids; the extrusive igneous rock equivalent of granite is rhyolite. Granite is nearly always massive and tough; these properties have made granite a widespread construction stone throughout human history. The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength lies above 200 MPa, its viscosity near STP is 3–6·1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. Granite is classified according to the QAPF diagram for coarse grained plutonic rocks and is named according to the percentage of quartz, alkali feldspar and plagioclase feldspar on the A-Q-P half of the diagram.
True granite contains both alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite; when a granitoid contains less than 10% orthoclase, it is called tonalite. A granite containing both muscovite and biotite micas is called two-mica granite. Two-mica granites are high in potassium and low in plagioclase, are S-type granites or A-type granites. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: Granite containing rock is distributed throughout the continental crust. Much of it was intruded during the Precambrian age. Outcrops of granite tend to form rounded massifs. Granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite occurs as small, less than 100 km2 stock masses and in batholiths that are associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are associated with the margins of granitic intrusions.
In some locations coarse-grained pegmatite masses occur with granite. Granite is more common in continental crust than in oceanic crust, they are crystallized from felsic melts which are less dense than mafic rocks and thus tend to ascend toward the surface. In contrast, mafic rocks, either basalts or gabbros, once metamorphosed at eclogite facies, tend to sink into the mantle beneath the Moho. Granitoids have crystallized from felsic magmas that have compositions near a eutectic point. Magmas are composed of minerals in variable abundances. Traditionally, magmatic minerals are crystallized from the melts that have separated from their parental rocks and thus are evolved because of igneous differentiation. If a granite has a cooling process, it has the potential to form larger crystals. There are peritectic and residual minerals in granitic magmas. Peritectic minerals are generated through peritectic reactions, whereas residual minerals are inherited from parental rocks. In either case, magmas will evolve to the eutectic for crystallization upon cooling.
Anatectic melts are produced by peritectic reactions, but they are much less evolved than magmatic melts because they have not separated from their parental rocks. The composition of anatectic melts may change toward the magmatic melts through high-degree fractional crystallization. Fractional crystallisation serves to reduce a melt in iron, titanium and sodium, enrich the melt in potassium and silicon – alkali feldspar and quartz, are two of the defining constituents of granite; this process operates regardless of the origin of parental magmas to granites, regardless of their chemistry. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was; the final texture and composition of a granite are distinctive as to its parental rock. For instance, a granite, derived from partial melting of meta
In geology, a rock's fabric describes the spatial and geometric configuration of all the elements that make it up. In sedimentary rocks, the fabric developed depends on the depositional environment and can provide information on current directions at the time of deposition. In structural geology, fabrics may provide information on both the orientation and magnitude of the strains that have affected a particular piece of deformed rock. Primary fabric — a fabric created during the original formation of the rock, e.g. a preferred orientation of clast long axes in a conglomerate, parallel to the flow direction, deposited by a fast waning current. Shape fabric — a fabric, defined by the preferred orientation of inequant elements within the rock, such as platy- or needle-like mineral grains, it may be formed by the deformation of equant elements such as mineral grains. Crystallographic preferred orientation — in plastically deformed rocks, the constituent minerals display a preferred orientation of their crystal axes as a result of dislocation processes.
S-fabric — a planar fabric such as cleavage or foliation. L-fabric — a linear fabric such as mineral stretching lineation where aggregates of recrystallised grains are stretched out into the long axis of the finite strain ellipsoid, where it forms the dominant fabric in a rock, it may be called an L-tectonite. Penetrative fabric — a fabric, present throughout the rock down to the grain scale, although this does depend on the scale at which the observations take place. Rock microstructure Texture Orientation tensor
Alaska is a U. S. state in the northwest extremity of North America, just across the Bering Strait from Asia. The Canadian province of British Columbia and territory of Yukon border the state to the east and southeast, its most extreme western part is Attu Island, it has a maritime border with Russia to the west across the Bering Strait. To the north are the Chukchi and Beaufort seas—southern parts of the Arctic Ocean; the Pacific Ocean lies to southwest. It is the largest U. S. state by the seventh largest subnational division in the world. In addition, it is the most sparsely populated of the 50 United States. Half of Alaska's residents live within the Anchorage metropolitan area. Alaska's economy is dominated by the fishing, natural gas, oil industries, resources which it has in abundance. Military bases and tourism are a significant part of the economy; the United States purchased Alaska from the Russian Empire on March 30, 1867, for 7.2 million U. S. dollars at two cents per acre. The area went through several administrative changes before becoming organized as a territory on May 11, 1912.
It was admitted as the 49th state of the U. S. on January 3, 1959. The name "Alaska" was introduced in the Russian colonial period when it was used to refer to the Alaska Peninsula, it was derived from an Aleut-language idiom. It means object to which the action of the sea is directed. Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America. It is technically part of the continental U. S. but is sometimes not included in colloquial use. S. called "the Lower 48". The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system; the state is bordered by Yukon and British Columbia in Canada, to the east, the Gulf of Alaska and the Pacific Ocean to the south and southwest, the Bering Sea, Bering Strait, Chukchi Sea to the west and the Arctic Ocean to the north.
Alaska's territorial waters touch Russia's territorial waters in the Bering Strait, as the Russian Big Diomede Island and Alaskan Little Diomede Island are only 3 miles apart. Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, the next largest state. Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the combined area of the next three largest states: Texas and Montana, it is larger than the combined area of the 22 smallest U. S. states. There are no defined borders demarcating the various regions of Alaska, but there are six accepted regions: The most populous region of Alaska, containing Anchorage, the Matanuska-Susitna Valley and the Kenai Peninsula. Rural unpopulated areas south of the Alaska Range and west of the Wrangell Mountains fall within the definition of South Central, as do the Prince William Sound area and the communities of Cordova and Valdez.
Referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States. As such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase; the region is dominated by the Alexander Archipelago as well as the Tongass National Forest, the largest national forest in the United States. It contains the state capital Juneau, the former capital Sitka, Ketchikan, at one time Alaska's largest city; the Alaska Marine Highway provides a vital surface transportation link throughout the area, as only three communities enjoy direct connections to the contiguous North American road system. Designated in 1963; the Interior is the largest region of Alaska. Fairbanks is the only large city in the region. Denali National Park and Preserve is located here. Denali is the highest mountain in North America. Southwest Alaska is a sparsely inhabited region stretching some 500 miles inland from the Bering Sea. Most of the population lives along the coast.
Kodiak Island is located in Southwest. The massive Yukon–Kuskokwim Delta, one of the largest river deltas in the world, is here. Portions of the Alaska Peninsula are considered part of Southwest, with the remaining portions included with the Aleutian Islands; the North Slope is tundra peppered with small villages. The area is known for its massive reserves of crude oil, contains both the National Petroleum Reserve–Alaska and the Prudhoe Bay Oil Field; the city of Utqiagvik known as Barrow, is the northernmost city in the United States and is located here. The Northwest Arctic area, anchored by Kotzebue and containing the Kobuk River valley, is regarded as being part of this region. However, the respective Inupiat of the No
A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep crevice in the rock. Fractures are caused by stress exceeding the rock strength, causing the rock to lose cohesion along its weakest plane. Fractures can provide permeability for fluid movement, such as water or hydrocarbons. Fractured rocks can make good aquifers or hydrocarbon reservoirs, since they may possess both significant permeability and fracture porosity. Fractures are forms of brittle deformation. There are two types of primary brittle deformation processes. Tensile fracturing results in joints. Shear fractures are the first initial breaks resulting from shear forces exceeding the cohesive strength in that plane. After those two initial deformations, several other types of secondary brittle deformation can be observed, such as frictional sliding or cataclastic flow on reactivated joints or faults. Most fracture profiles will look like either a blade, ellipsoid, or circle.
Fractures in rocks can be formed either due to tension. Fractures due to compression include thrust faults. Fractures may be a result from shear or tensile stress; some of the primary mechanisms are discussed below. First, there are three modes of fractures that occur: Mode I crack – Opening mode Mode II crack – Sliding mode Mode III crack – Tearing mode For more information on this, see fracture mechanics; this deformation creates propagation of fractures into unfractured rock, when the rock is subjected to tensile stress. In the case of a homogenous stress field, the crack will propagate in the direction perpendicular to the least principal stress. Engineers studying elasticity found that the stress due to a load distant from the region of interest is concentrated around material flaws. A. W. Griffith took this example and applied the concept of stress concentration to the ends of fractures. Griffith asserted that all material have microcracks or flaws where the stress concentration occurs, that these were the flaws where, under increasing stress, fractures propagate.
As a result, these pre-existing flaws were named Griffith cracks, allow the conceptual assumption that rocks are weak. From this assumption, tensile fracture development may be examined; the first form is in axial stretching'. In this case, remote tensile stress is applied, allowing microcracks to open throughout the tensile region; as these cracks open up, the stresses at the crack tips intensify exceeding the rock strength and allowing the fracture to propagate. This can occur at times of rapid overburden erosion. Folding can provide tension, such as along the top of an anticlinal fold axis, where the tensile forces associated with the stretching of the upper half of the layers during folding can induce tensile fractures parallel to the fold axis. Tensile fracturing may be induced by applied compressive loads along an axis, which results in longitudinal splitting. In this situation, tiny tensile fractures form parallel to the loading axis, however the load forces any other microfractures closed.
To picture this, imagine an envelope, with loading from the top. A load is applied on the top edge, the sides of the envelope open outward though nothing was pulling on them. Rapid deposition and compaction can sometimes induce these fractures. For Griffith Fractures, there are several key equations. KI = Δσ½when KIC = KIthe fracture is propagated, where KI is the stress concentration at the fracture tip, Δσ is the difference in stress applied along the fracture area and the in-situ stress, a is the half length of the fracture. W = 4∙∙Δσ∙½where W is the fracture width at x distance from the center, ν is the Poisson's ratio, E is the Young's Modulus of Elasticity, Δσ is the difference in stress applied along the fracture area and the in-situ stress, a is the half length of the fracture. Another tensile fracture mechanism is hydraulic fracturing. In a natural environment, this occurs when a combination of rapid sediment compaction and thermal fluid expansion causes the pore fluid pressure to exceed the pressure of the least principal normal stress.
When this occurs, a tensile fracture opens perpendicular to the plane of least stress. Tensile fractures are always referred to as joints, which are fractures where no appreciable slip or shear is observed. Describing joints can be difficult without visuals; the following are descriptions of typical natural fracture joint geometries that might be encountered in field studies: Plumose Structures are fracture networks that form at a range of scales, spread outward from a joint origin. The joint origin represents a point; the mirror zone is the joint morphology closest to the origin that results in smooth surfaces. Mist zones exist on the fringe of mirror zones and represent the zone where the joint surface roughens. Hackle zones predominate after mist zones, where the joint surface begins to get rough; this hackle zone severity designates barbs. Orthogonal Joints occur when the joints within the system occur at mutually perpendicular angles to each other. Conjugate Joints occur when the joints intersect each other at angles less than ninety degrees.
Systematic Joints are joint systems in which all the joints are parallel or subparallel, maintain the same spacing from each oth
Monzonite is an igneous intrusive rock. It is composed of equal amounts of plagioclase and alkali feldspar, with less than 5% quartz by weight, it may contain minor amounts of hornblende and other minerals. If quartz constitutes greater than 5%, the rock is termed a quartz monzonite. If the rock has a greater percentage of alkali feldspar, it grades into a syenite. With an increase in calcic plagioclase and mafic minerals the rock type becomes a diorite; the volcanic equivalent is the latite. Monzonite was named after the Monzoni range in Val di Fassa where it is abundant; as rock definitions have been systematized and codified, this association has lost any relevance to the rock's definition. QAPF diagram – Classification system for igneous rocks
A batholith is a large mass of intrusive igneous rock, larger than 100 square kilometres in area, that forms from cooled magma deep in the Earth's crust. Batholiths are always made of felsic or intermediate rock types, such as granite, quartz monzonite, or diorite. Although they may appear uniform, batholiths are in fact structures with complex histories and compositions, they are composed of multiple masses, or plutons, bodies of igneous rock of irregular dimensions that can be distinguished from adjacent igneous rock by some combination of criteria including age, texture, or mappable structures. Individual plutons are solidified from magma that traveled toward the surface from a zone of partial melting near the base of the Earth's crust. Traditionally, these plutons have been considered to form by ascent of buoyant magma in large masses called plutonic diapirs; because the diapirs are liquified and hot, they tend to rise through the surrounding native country rock, pushing it aside and melting it.
Most diapirs do not reach the surface to form volcanoes, but instead they slow down and solidify 5 to 30 kilometers underground as plutons. An alternate view is that plutons are formed not by ascent of large magma diapirs, but rather by aggregation of smaller volumes of magma that ascend as dikes. A batholith is formed; some batholiths are mammoth, paralleling past and present subduction zones and other heat sources for hundreds of kilometers in continental crust. One such batholith is the Sierra Nevada Batholith, a continuous granitic formation that makes up much of the Sierra Nevada in California. An larger batholith, the Coast Plutonic Complex, is found predominantly in the Coast Mountains of western Canada. A batholith is an exposed area of continuous plutonic rock that covers an area larger than 100 square kilometers. Areas smaller than 100 square kilometers are called stocks. However, the majority of batholiths visible at the surface have areas far greater than 100 square kilometers; these areas are exposed to the surface through the process of erosion accelerated by continental uplift acting over many tens of millions to hundreds of millions of years.
This process has removed several tens of square kilometers of overlying rock in many areas, exposing the once buried batholiths. Batholiths exposed at the surface are subjected to huge pressure differences between their former location deep in the earth and their new location at or near the surface; as a result, their crystal structure expands over time. This manifests itself by a form of mass wasting called exfoliation; this form of weathering causes convex and thin sheets of rock to slough off the exposed surfaces of batholiths. The result is clean and rounded rock faces. A well-known result of this process is Half Dome in Yosemite Valley. Aswan Granite Batholith Cape Coast Batholith, Ghana Darling Batholith, South Africa Hook granite massif, Zambia Mubende Batholith, Uganda Antarctic Peninsula Batholith Queen Maud Batholith Angara-Vitim batholith, Siberia Bhongir Fort Batholith, India Gangdese batholith, Himalaya Trans-Himalayan Batholith, Himalaya Kalba-Narym batholith, Kazakhstan Karakorum Batholith, Himalaya Tak batholith, Thailand Tien Shan batholith, Central Asia Bindal Batholith, Norway Cornubian batholith, England Corsica-Sardinia Batholith Donegal batholith, Ireland Leinster Batholith, Ireland Mancellian batholith, France North Pennine Batholith, England Ljusdal Batholith, Sweden Mt-Louis-Andorra Batholith Riga Batholith, Latvia Salmi Batholith, Republic of Karelia, Russia Sunnhordaland Batholith, Norway Transscandinavian Igneous Belt and NorwayRevsund Massif Rätan Batholith Småland–Värmland Belt Bald Rock Batholith Boulder Batholith British Virgin Islands Chambers-Strathy Batholith Town Mountain Granite batholith, Texas Golden Horn Batholith Idaho Batholith Ilimaussaq Batholith, Greenland Kenosha Batholith Ruby Mountains Rio Verde Batholith, Mexico Sierra Nevada Batholith South Mountain Batholith, Nova Scotia Peninsular Ranges and Southern California Stone Mountain Pike's Peak Granite Batholith Chilliwack batholith Wyoming batholith Cullen Batholith, Australia Kosciuszko Batholith, Australia Moruya Batholith, Australia Median Batholith, New Zealand New England Batholith, Australia Achala Batholith, Argentina Antioquia Batholith, Colombia Guanambi Batholith, Brazil Parguaza rapakivi granite Batholith and Colombia Cerro Aspero Batholith, Argentina Coastal Batholith of Peru Colangüil Batholith, Argentina Cordillera Blanca Batholith, Peru Vicuña Mackenna Batholith, Chile Elqui-Limarí Batholith and Argentina Futrono-Riñihue Batholith, Chile Illescas Batholith, Uruguay Coastal Batholith of central Chile Panguipulli Batholith, Chile Patagonian Batholith and Argentina North Patagonian Batholith South Patagonian Batholith Laccolith Sill Stock Volcanic plug Plummer, McGeary, Physical Geology, Eighth Edition pages 61–63 ISBN 0-697-37404-1 Glazner, Coleman, Taylor, Are plutons assembled over millions of years by amalgamation from small magma chambers?, GSA Today: Vol. 14, No.
4, pp. 4–11 Idaho Batholith The Cornubian Batholith