Formation[ edit ] Sinkholes near the Dead Seaformed when underground salt is dissolved by freshwater intrusion, due to continuing sea-level drop. Collapse sinkhole in gypsumnear Madrid, central Spain. Natural processes[ edit ] Sinkholes may capture surface drainage from running or standing water, but may also form in high and dry places in specific locations. Sinkholes that capture drainage can hold it in large limestone caves.
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These caves may drain into tributaries of larger rivers. Occasionally a sinkhole may exhibit a visible opening into a cave below.
Sinkholes are common where the rock below the land surface is limestone or other carbonate rocksalt bedsor in other soluble rocks, such as gypsum that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains. As the rock dissolves, spaces and caverns develop underground. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support.
Then, a sudden collapse of the land surface can occur. Pinge Collapse formed by rainwater leaking through pavement and carrying soil into a ruptured sewer pipe. Collapses, commonly incorrectly labeled as sinkholes also occur due to human activity, such as the collapse of abandoned mines and salt cavern storage in salt domes in places like LouisianaMississippi and Texas. More commonly, collapses occur in urban areas due to water main breaks or sewer collapses when old pipes give way.
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They can also occur from the overpumping and extraction of groundwater and subsurface fluids. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole.
The entire surface water flow of the Alapaha River near Jennings, Florida goes into a sinkhole leading to the Floridan Aquifer groundwater Sinkholes tend to occur in karst landscapes. Sincethe U.
The Plight of American Manufacturing
A once-robust system of "traditional engineering" -- the invention, design, and manufacture of products -- has been replaced by financial engineering. Without a vibrant manufacturing sector, Wall Street created money it did not have and Americans spent money they did not have. Americans stopped making the products they continued to buy: America's economic elite has long argued that the country does not need an industrial base. The economies in states such as California and Michigan that have lost their industrial base, however, belie that claim.
Without an industrial base, an increase in consumer spending, which pulled the country out of past recessions, will not put Americans back to work. Without an industrial base, the nation's trade deficit will continue to grow.
Without an industrial base, there will be no economic ladder for a generation of immigrants, stranded in low-paying service-sector jobs. Without an industrial base, the United States will be increasingly dependent on foreign manufacturers even for its key military technology.
For American manufacturers, the bad years didn't begin with the banking crisis of Sincethe country has lost 42, factories, including 36 percent of factories that employ more than 1, workers which declined from 1, toand 38 percent of factories that employ between and employees from 3, to 1, An additional 90, manufacturing companies are now at risk of going out of business.
Long before the banking collapse ofsuch important U. Manufacturing employment dropped to The last time fewer than 12 million people worked in the manufacturing sector was in In Octobermore people were officially unemployed When a factory closes, it creates a vortex that has far-reaching consequences. The Milken Institute estimates that every computer-manufacturing job in California creates 15 jobs outside the factory.
Close a manufacturing plant, and a supply chain of producers disappears with it. Dozens of companies get hurt: The burden spreads to local restaurants, cultural establishments, shopping outlets, and then to the tax base that supports police, firemen, schoolteachers, and libraries.
American companies are among the most efficient in the world. The nation's steel industry, for instance, produces 1 ton of steel using two man-hours. A comparable ton of steel in China is produced with 12 man-hours, and Chinese companies produce three times the amount of carbon emissions per ton of steel.
The same kinds of comparisons are true for other industries. But American companies have difficulty competing against foreign countries that undervalue their currencies, pay health care for their workers; provide subsidies for energy, land, buildings, and equipment; grant tax holidays and rebates and provide zero-interest financing; pay their workers poverty wages that would be illegal in the United States, and don't enforce safety or environmental regulations.
Proponents of free trade and outsourcing argue that the United States remains the largest manufacturing economy in the world. As for our balance of trade, U. Those imported goods represented Our trade deficit will not diminish absent a significant increase in domestic manufacturing.
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Those unconcerned about the decline of American manufacturing might want to read Winwood Reade's volume The Martyrdom of Man, in which he chronicled the economy of ancient Rome: That was their return cargo. American Chung Nam, which exportedcontainers of waste paper to its Chinese sister company, Nine Dragons Paper.
By comparison, Wal-Mart importedcontainers of sophisticated manufactured products from overseas factories into the United States, followed by TargetcontainersHome Depotcontainersand Sears, which owns K-Martcontainers. Our own Ostia Road. The United States is not losing old, inefficient industries that produce "buggy whip" products for which there is no more demand.
There is ample demand for televisions, sporting goods, bicycles, blenders, hearing aides, golf clubs, laptops, and desktops. The industries that have left the United States are still producing products that are in demand. Without a printed circuit board PCB industry, for instance, a country cannot expect to have an industrial foundation for high-tech innovation.
PCB manufacturers accounted for only 8 percent of global production indown from 26 percent in China's share of the global PCB market in was Asia now controls 84 percent of the global production of printed circuit boards, which are used in tens of thousands of different products. PCB industry is in free fall.