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CREATION ART

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  • Photobucket Songs of Earth's Creations. In an endless cycle of eons she creates and destroys masterpieces, reusing her building materials to create anew. From death comes life.Photobucket
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    Saturday, January 19, 2008

     

    Icelanders Battle Volcano - Save Port

    The people of Iceland must repeatedly battle one of the most violent forces of nature - volcanic eruptions. The same forces that created Iceland threaten to destroy Man's intrusions.

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    Formation of Iceland

    http://en.wikipedia.org/wiki/Iceland_plume

    Iceland plume

    The Iceland Plume is an upwelling of anomalously hot rock in the Earth's mantle beneath Iceland whose origin probably lies at the boundary between the core and the mantle at ca. 2880 km depth. It is generally thought to be the cause of the formation of Iceland and its volcanism, which characterizes the island to the present day, according to the plume theory of W. Jason Morgan.

    Geological history

    The plume, which bears the name of Iceland and lies roughly beneath the center of the island, is considerably older than Iceland. Volcanic rocks related to it are found to both sides of the coast of southern Greenland and had their ages determined to lie between 58 and 64 million years; this coincides with the opening of the north Atlantic in the late Paleocene and early Eocene. It is generally thought that the volcanism was caused by the flow of hot material from the plume head into regions beneath the lithosphere which had previously been thinned by rifting and produced large amounts of melt there. The exact position of the plume at that time is controversial, but was probably beneath central Greenland; it is also not entirely clear whether the plume had ascended from the deep mantle only at that time or whether it is much older and also responsible for the old volcanism in northern Greenland, the Ellesmere Island Volcanics on Ellesmere Island, and in the Arctic Ocean (Alpha Ridge). All of these volcanics are part of the High Arctic Large Igneous Province. (see url for remainder of article)

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    http://en.wikipedia.org/wiki/Iceland

    Excerpt: (for complete article, access url)

    Geological activity

    A geologically old land, Iceland is located on both a geological hot spot, thought to be caused by a mantle plume, and the Mid-Atlantic Ridge, which runs right through it. This combined location means that geologically the island is extremely active, having many volcanoes, notably Hekla, Eldgjá, and Eldfell. The volcanic eruption of Laki in 1783–1784 caused a famine that killed nearly a quarter of the island's population;[7] the eruption caused dust clouds and haze to appear over most of Europe and parts of Asia and Africa for several months after the eruption.

    There are also many geysers in Iceland, including Geysir, from which the English name is derived. With this widespread availability of geothermal power, and also because of the numerous rivers and waterfalls that are harnessed for hydroelectricity, most residents have hot water and home heat for a low price. The island itself is composed primarily of basalt, a low-silica lava associated with effusive volcanism like Hawaii. There is, however, a variety of different kinds of volcanoes in Iceland, many of which produce more evolved lavas such as rhyolite and andesite.

    Dettifoss, the most powerful waterfall in Europe, is located in north-eastern Iceland.
    Dettifoss, the most powerful waterfall in Europe, is located in north-eastern Iceland.

    Iceland controls Surtsey, two of the youngest islands in the world. It rose above the ocean in a series of volcanic eruptions between November 8, 1963 and June 5, 1968.[6]

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    Because of its volcanic activity, Iceland's inhabitants must deal with eruptions quite often. To save their port, vital to the existence of the town, the residents of a threarened town fight back - and win.


    Eldfell, Heimaey, Iceland Location: 63.4N, 20.3W
    Elevation: 915 feet (279 m)
    Last Updated: 10 April 2001


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    The 1973 eruption on the island of Heimaey is a classic example of the struggle between man and volcanoes. With a heroic effort the people of Iceland saved the town of Vestmannaeyjar and the country's most important fishing port.

    Except where noted, all photographs are by the late Svienn Eirikksen, fire marshal of the town of Vestmannaeyjar. Photographs courtesy of the U.S. Geological Survey.

    The island of Heimaey with the growth of the island in 1973, the location of the eruptive fissure, and the location of Eldfell, the 1973 cone. Modified from Williams and Moore, 1983.

    View of Heimaey before the eruption. The town of Vestmannaeyjar and the harbor are in the foreground. Helgafell, a prehistoric cone, is in the background on the right. From Williams and Moore, 1983.

    Eldfell ("fire mountain" in Icelandic) is a volcano on the island of Heimaey in the Vestmannaeyjar archipelago 15 miles (25 km) south of Iceland. In January of 1973, an eruption began along a 1.5 mile (2 km) long fissure not far from the center of the town of Vestmannaeyjar. The fissure extended across the entire island, producing a spectacular curtain of fire. Nearly all of the island's 5,300 residents were evacuated to the mainland.

    Within two days, activity became localized to a central vent and fire fountains constructed a cinder and spatter cone 350 feet (100 m) above sea level.

    Strong winds blew tephra from the eruption and buried homes in the town Vestmannaeyjar.

    Massive block lava flows threatened the town and the fishing port.

    A submarine eruption cut the cable that supplied power from the mainland. The initial eruption rate was close to 130 cubic yards (100 cubic meters) per second. By the middle of April, the eruption rate had dropped to 7 cubic yards (5 cubic meters) per second. The eruption stopped in early July.

    About 70 homes and farms were buried under tephra and 300 buildings were burned by fires or buried under lava flows.

    This eruption is famous because the Icelanders sprayed sea water on the lava to slow and stop its movement. It was the largest effort ever exerted to control volcanic activity. More than 19 miles (30 km) of pipe and 43 pumps were used to deliver sea water at rate up to 1.3 cubic yards (1 cubic meters) per second. By the end of the eruption 8 million cubic yards (6 million cubic meters) of water had been pumped onto the flows.

    View in July 1974 of the same scene as above after removal of the lava. The building were restored. From Williams and Moore, 1983.

    The town of Vestmannaeyjar and the harbor after the eruption. Eldfell and the 1973 lava flows are just beyond the town. Photograph by Robin Holcomb, U.S. Geological Survey.

    Not only did the tremendous efforts save the port they actually improved it. The residents returned to rebuild their town and even used the heat from the cooling lava to construct a district heating system. This vertical aerial photograph of the island shows the improved harbor, Helgafell and Eldfell cones, and the new land added to the island. Photograph by Iceland Geodetic Survey, September, 8, 1973. From Williams and Moore, 1983.

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    Photos of Iceland:



    Image:Iceland Dettifoss 1972-4.jpg

    Dettifoss Falls

    Dettifoss: most powerful waterfall in Europe

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    Sunday, January 13, 2008

     

    cenotes


    Swimmers and Divers at a cenote





    Cenotes - photos of underwater views

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    Sacred Cenote..........................................photo

    cenotes
    http://en.wikipedia.org.wiki/Cenotes

    [edited for length - excerpts from]

    A cenote (pronounced in Mexican Spanish [seˈnoˌte] and in English [səˈnəʊˌteɪ], plural: cenotes; from Yucatec Maya dzonot) is a type sinkhole containing groundwater typically found in the Yucatán Peninsula and some nearby Caribbean islands. The term is derived from a word used by the low-land Maya to refer to any location where groundwater is accessible.


    Definition and description

    Cenotes are surface connections to subterranean water bodies [1]. While the most well-known cenotes are large open water pools measuring tens of metres in diameter, such as those at Chichén Itzá, the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water. The term cenote has also been used to describe similar karst features in other countries such as Cuba and Australia, in addition to the more generic term of sinkholes.

    Cenote water is often very clear, as the water comes from rain water infiltrating slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow at velocities ranging from 1 to 1000 meters per year. In many cases, cenotes are areas where sections of cave roof have collapsed revealing an underlying cave system and the water flow rates here may be much faster: up to 10,000 meters per day[2]. Cenotes around the world attract cave divers who have documented extensive flooded cave systems through them, some of which have been explored for lengths of 100 kilometers or more.

    Geology and hydrology

    Cenote in Quintana Roo
    Cenote in Quintana Roo

    Formation

    Cenotes are formed by dissolution of rock which creates a subsurface void, which may or may not be linked to an active cave system, and the subsequent structural collapse of the rock ceiling above the void. The rock that falls into the water below will then be slowly removed by further dissolution, creating space for more collapse blocks. The rate of collapse increases during periods when the water table is below the ceiling of the void, since the rock ceiling is no longer buoyantly supported by the water in the void. Cenotes may be fully collapsed creating an open water pool, or partially collapsed with some portion of a rock overhang above the water. The stereotypical cenotes often resemble small circular ponds, measuring some tens of meters in diameter with sheer drops at the edges. Most cenotes however require some degree of stooping if not crawling to access the water.

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    Types of cenotes

    In 1936, a simple morphometry based classification system for cenotes was presented [3]. Cenotes-cántaro (Jug, or Pit cenotes) are those with a surface connection narrower than the diameter of the water body; Cenotes-cilíndricos (Cylinder cenotes) are those with strictly vertical walls; Cenotes-aguadas (Basin cenotes) are those with shallow water basins; and grutas (Cave cenotes) are those having a horizontal entrance with dry sections. [...]

    Cenotes and the Maya

    Cenotes have long been the principal sources of water in much of the Yucatán Peninsula. The region has almost no rivers and only a few lakes, often marshy. Cenotes are widely distributed, and supply better-quality water year-round. Major Maya settlements required access to adequate water supplies, and therefore cities, including the famous Chichén Itzá, were built around these natural wells. Some cenotes like the Cenote of Sacrifice in Chichén Itzá played an important role in Maya rites. Believing that these pools were gateways to the other world, the Maya sometimes threw valuable items into them. The discovery of golden sacrificial artifacts in some cenotes led to the archaeological exploration of most cenotes in the first part of the 20th century. Edward Herbert Thompson, an American diplomat who had bought the Chichén Itzá site, began dredging the Sacred Cenote there in 1904. He discovered human skeletons and sacrificial objects confirming a local legend, the Cult of the Cenote, involving human sacrifice to the rain gods (Chaacs) by ritual casting of victims and objects into the cenote.

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    Notable cenotes

    Mexico, Yucatan Peninsula

    Mexico, Central and Northern region

    United States


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    Saturday, January 12, 2008

     

    Sinkhole Formation

    One cannot call sinkholes a work of art but they are a part of the processes of this planet. The only sinkholes that may be called beautiful are those ancient ones that have filled with water and formed a lake, or those which have collapsed into caves that eventually became lovely, fascinating places having their own odd beauty.
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    http://www.dnr.mo.gov/geology/geosrv/geores/sinkholes_formation.htm

    Sinkhole Formation

    A sinkhole (also called a doline) is a depressed area usually formed by solution of surficial bedrock or collapse of underlying caves. The surface expression of a sinkhole is typically a conical depression or area of internal drainage. Sinkholes range in size from several square yards to hundreds of acres. They may be quite shallow or may extend hundreds of feet deep. Sinkholes are places where there is rapid recharge (replenishing) of groundwater from the surface and, therefore, are areas of potential groundwater contamination. For this reason, managing surface water and waste disposal in sinkhole-prone areas are important to maintaining good groundwater quality.

    The diagrams below conceptually illustrate the stages of sinkhole formation. Actual conditions in nature may be very different than those illustrated. For instance, the rock and soil layers may be thicker or thinner, the fracture and cave passage may be larger or smaller, and the surfaces are likely to be much more irregular in shape.


    stage 1

    stage 2

    Stage 1
    For a sinkhole to form there must be an opening in the bedrock surface that allows overlying soil to move downward into a cave passage. This stage illustrates a solution-widened fracture in the bedrock choked with soil.

    Stage 2
    Soil that collected in the cave passage in Stage 1 has been carried away by flowing water.



    stage 3

    stage 4

    Stage 3
    Soil that collected in the fracture or bedrock opening collapses into the cave or is washed into the cave by water movement from the soil into the cave.

    Stage 4
    Additional soil movement or collapse causes a void to form at the bedrock surface.



    stage 5

    stage 6

    Stage 5
    The void enlarges and moves upward in the soil profile, a process known as stoping.

    Stage 6
    Eventually the void enlarges until only a thin layer of soil remains at the surface.



    stage 7

    stage 8

    Stage 7
    Finally the thinned soil roof can no longer support itself and creates a surface collapse that may or may not choke the hole in the bedrock. Typically the initial appearance is a steep-sided hole at the surface several feet deep with a floor of soil that used to be at the surface.

    Stage 8
    If the bedrock throat of the sinkhole remains plugged with the collapsed soil, the surface hole may fill with other eroded soil.

    In some instances the unstable, steep-sided surface hole may widen into a conical depression, like the upper portion of an hour glass. If the throat of the sinkhole remains open, surface water will drain readily. If the throat becomes plugged with soil, water may pond temporarily or permanently in the depression, forming a sinkhole lake. The entire process may repeat itself by starting over.



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    http://www.mme.state.va.us/Dmr/OUB/Brochures/sink.html

    For complete article, access above url.

    Excerpts from above article:

    SINKHOLES


    In Virginia the formation and modification of sinkholes (also known as sinks, dolines and dolinas) is a natural process in areas underlain by limestone and other soluble rock. The location and rate at which sinkholes form can be affected by man's activities. Sinkholes are basin-like, funnel-shaped, or vertical sided depressions in the land surface. In general, sinkholes form by the subsidence of unconsolidated materials or soils into voids created by the dissolution of the underlying soluble bedrock. The rock exposed in a collapsed sinkhole is usually weathered and rounded, but some sinkholes contain freshly broken rock along their steep sides. Freshly broken rock may indicate that the sinkhole has formed by the collapse of a cave (naturally occurring) or a mine (man made). Where sinkholes and caves have formed by the dissolution of soluble rock, such as limestone, dolomite, and gypsum, surface water is uncommon and streams may sink into the ground. This type of topography, formed by dissolution, is referred to as karst terrain. In karst terrain, sinkholes are input points where surface water enters the groundwater sustem.



    Potential Sinkhole Problems
    There are three types of potential problems associated with the existence or formation of sinkholes: subsidence, flooding, and pollution. Sinkholes are the result of differential subsidence of the land surface. The term subsidence is commonly used to imply a gradual sinking, but it also can refer to an instananeoust or catastrophic collapse. Sinkholes result from various mechanisms (Sowers, 1976), including consolidation from loading, consolidation from dewatering, hydraulic compaction, settling as materials are removed by groundwater flow, stoping or raveling of materials into a void, and instantaneous collapse into a void. Although the formation of sinkholes is a natural process in karst terrains, man-made modifications to the hydrology of these areas commonly results in the acceleration of this process.

    [...]Patterns of pumping of high yield wells over extended periods of time can result in large as well as rapid drawdowns of the water table. Where such rapid and large drawdowns occur in unconsolidated materials, sinkhole collapse can be catastrophic and subsidence can be extensive over the area subject to the drawdown (Foose, 1967 and 1968). Sinkhole formation can also occur above solutionally enlarged fractures, which have fomed caves or "mudseams". Water-table drawdowns can cause soil voids to migrate along solution features eventually leading to sinkhole formation at a distance from the well.

    Sinkhole subsidence is associated also with soil piping. Water leaking from culverts, or other drainage structures can create a void beneath the drainage structure by compaction or internal scour of the soil. This reduction in support can result in displacement of the leaking structure and an increase in leakage or breakage. The void may increase in size to the extent that the soil has insufficient strength to support itself with subsequent failure leading to the fomation of a steep sided collapse sinkhole. The recognition of water mark stains on the fracture surfaces and joints of drainage structures are indicators of this type of sinkhole formation.

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    [A large sinkhole of the soil piping type opened up in a neighbor's lawn and under her front sidewalk. City workers discovered a leak in the underground water main had washed away the soil and caused the sinkhole. My friend's husband almost caused more collapse of the surface soil and grass . He narrowly escaped falling into the deep cavity by stepping too close to the hole. The soil and grass at the edge of the hole formed a shelf under which the cavity belled out. The shelf could not support his weight and broke away. NEVER get near the edge of a sinkhole!]

    Wet soil weighs more and has less strength than if it were dry. If the strength of the wet soil is insufficient the soil arch will fail. A number of adjacent voids may coalesce to form a large void. If the strength of the dry soil is sufficient to support the soil arch, the wet soil failure will proceed only to the dry soil above the former water level. Subsequent periods of extended heavy rainfall may wet the soil sufficiency to reduce its strength below that necessary to support the soil arch and failure would propagate to the surface and form a steep-sided collapse sinkhole (Figure 1). Patterns of pumping of high yield wells over extended periods of time can result in large as well as rapid drawdowns of the water table. Where such rapid and large drawdowns occur in unconsolidated materials, sinkhole collapse can be catastrophic and subsidence can be extensive over the area subject to the drawdown (Foose, 1967 and 1968). Sinkhole formation can also occur above solutionally enlarged fractures, which have fomed caves or "mudseams". Water-table drawdowns can cause soil voids to migrate along solution features eventually leading to sinkhole formation at a distance from the well.

    Sinkhole subsidence is associated also with soil piping. Water leaking from culverts, or other drainage structures can create a void beneath the drainage structure by compaction or internal scour of the soil. This reduction in support can result in displacement of the leaking structure and an increase in leakage or breakage. The void may increase in size to the extent that the soil has insufficient strength to support itself with subsequent failure leading to the fomation of a steep sided collapse sinkhole. The recognition of water mark stains on the fracture surfaces and joints of drainage structures are indicators of this type of sinkhole formation.

    [Figure 1] Disposal of storm water in sinkholes or shallow dry wells can induce subsidence. Adjacent to the drainage input additional sinkholes may form. Subsidence results from a combination of factors, which may include hydraulic compaction, soil piping, and increases in the range of fluctuation of the water table.

    The collapse of a void created by underground mining activities is another mode of sinkhole formation. Voids, created by the solution mining of salt and the conventional underground mining of gypsum, limestone, and coal, have collapsed to form sinkholes in Virginia.

    Sinkhole flooding can develop from a number of conditions, but two man-made conditions are the most common causes in Virginia: the plugging of natural sinkhole drains by sediment and the overwhelming of natural snkhole drains by increases in runoff due to artificial surfaces. Inadequate erosion control during construction can result in the plugging of natural sinkhole drains by sediment-laden runoff. The accompanying restriction of subsurface drainage causes an increase in ponding or flooding. Increased runoff from roads, parking lots, and structures is the most significant cause of sinkhole flooding. Much of the precipitation that would have percolated through a vegetated soil cover is introduced rapidly into surface and subsurface (input through sinkholes) drainage networks. Increases in runoff have been reported to range from 48 percent for area of suburban housing to 153 percent or more for industrial or commercial areas (Aley and Thomson, 1981). Such increases in runoff can exceed the drainage capacity of natural sinkhole drain and result in ponding or flooding. In severe cases, excessive runoff can overwhelm the capacity of the natural subsurface drainage systems of sinkholes, causing water to back-up and flood snkholes up-system (Crawford, 1981). An example of an overwhelmed natural subsurface drainage conduit occurred in Virginia in November, 1985. A stream of water estimated with a peak flow of 50,000 gallons per minute was observed flowing from a normally dry sinkhole during this major storm event(D. W. Slifer, 1988, personal commmication).

    The pollution of groundwater resources is an ever present problem in karst areas. Sinkholes have long been used as dumps for waste materials. The dumping of solid wastes, such as dead animals, garbage, and refuse, into sinkholes is a major hazard to groundwater resources. It is also prohibited by existing State law (Code of Virginia, Title 10, chapter 12.2, section 10-150.14). Liquid wastes dumped into sinkholes can enter the gromdwater system undiluted through the underground drainage routes or conduits. An excellent principle is to never put anything in a sinkhole that you would not want in your drinking water.




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    Sinkholes

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    Several houses fell into this sinkhole in Guatemala; 2 people were killed.
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    Other Sinkholes

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    Sinkholes Open In Highways and Construction Sites

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    Sinkhole Opens Under Sidewalks

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    Hole In Lake By Dam


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    Sinkholes Open Under Homes

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    This building didn't fall into sinkhole but was structurally damaged and had to be demolished.

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    Other Sinkholes - smaller

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    Ancient Sinkholes Become Caves or open into a cave.


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    Interior view of cave/sinkhole
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    Some sinkholes lead to caves, sometimes filled with water. See Cenotes. Some cenotes can be as deep as 70 feet to cave below. Some cenotes were used as sacrificial offering sites by early societies in central and south America. Modern divers like to explore water filled cave systems through a cenote.

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