Which natural resource is part of the lithosphere

The outer part of the lithosphere consists of the crust. Yes, it is a natural resource. Yes, the crust of the Earth is part of the lithosphere. The biggest natural resource in the country was timber. The natural resource to use in that situation was coal.

Yes, uranium is a natural resource. Yes, It is a natural resource. Yes, air is Natural Resource. Yes, cooper is a natural resource. No gasoline is not a natural resource. Log in. Natural Resources. Study now. See Answer. Best Answer. Study guides. Business Globalization 26 cards. How do you use ebullient in a sentence. A tax on imports designed to discourage their sale by making them more expensive than local goods. What is a typical result of the existence of clans and tribes in a given territory.

What effects can modern farming techniques have on world biodiversity. United Nations 30 cards. Humus is a major factor in deciding the soil structure because it causes the soil to become more porous and allows water and air to penetrate deep underground.

The mineral nutrients that are found in a particular soil depend on the rocks it was formed from. The nutrient content of a soil, the amount of humus present in it and the depth of the soil are some of the factors that decide which plants will thrive on that soil.

Within it the air, water, rocks and soil and the living creatures, form structural and functional ecological units, which together can be considered as one giant global living system, that of our Earth itself.

Within this framework, those characterized by broadly similar geography and climate, as well as communities of plant and animal life can be divided for convenience into different bio-geographical realms.

These occur on different continents. Within these, smaller bio-geographical units can be identified on the basis of structural differences and functional aspects into distinctive recognizable ecosystems, which give a distinctive character to a landscape or waterscape.

The simplest of these ecosystems to understand is a pond. It can be used as a model to understand the nature of any other ecosystem and to appreciate the changes over time that is seen in any ecosystem. Are you worried or stressed? Click here for Expert Advice. Comment 0. Post Comment. View Source wetland. View Source Adapted from "aquifer. Wikimedia Foundation.

Of course, humans are also impacted. Drinking and bathing in water that is polluted directly harms humans, especially small children and the elderly, and toxic chemicals that accumulate in aquatic top predators fish and sea mammals can make some species unsafe to eat. The World Health Organization estimates that 3. Feeding and providing water for a growing human population of over 7 billion is both a necessity and a challenge.

Read more about many aspects of the world's water at water. Fracking also mixes freshwater with over different solvents, acids, and toxic chemicals, rendering the water contaminated with carcinogens, and toxic chemicals known to disrupt the nervous, endocrine, immune, cardiovascular, and respiratory systems. Watch this short film which describes fracking and its potential opportunities and dangers. Fracking impacts both water quantity and quality.

As explained in the FWW report, in fracking, a toxic chemical and water solution is injected underground under high pressure in order to open up cracks in the ground and push the natural gas toward the surface.

However, sometimes this chemical and water solution will come to the surfaces itself. Along with the chemicals originally put into the solution, this waste water can surface with additional toxic natural elements like heavy metals chromium, strontium, barium, zinc, lead, arsenic and radioactive materials like Radium, all of which naturally occur deep underground. Figure Open pit gold mine in Australia. Similarly, mining of metals and other minerals from the lithosphere requires very high volumes of fresh water, and typically produces problematic toxic waste water.

Open pit mining Figure 21 is a common method of natural resource extraction, which exposes toxic substances that naturally occur underground.

Weathering by rain and wind dissolve and move toxic mining chemicals into streams, lakes, wetlands, and ultimately the oceans. Near Silverton, Colorado, in the United States, 3. Figure Toxic waste water from an abandoned gold mine in southern Colorado, USA. The bright yellow water contains high concentrations of acid and heavy metals including lead, cadmium, aluminum, copper, and arsenic. The biosphere refers to the sum total of all life forms on Earth, and these life forms inhabit the atmosphere primarily microorganisms drifting in the wind and in clouds , the lithosphere land organisms are referred to as terrestrial; those belowground are called subterranean Below the surface of the Earth; underground.

View Source Adapted from "subterranean. Plants and animals also serve other important uses for humans, including providing fibers that can be woven into cloth or used to make paper, and fur, horn, and bone that can be used to make clothing, tools, and jewelry.

We use wood for building materials and as fuel for heat or cooking. Oils and fats are used to make materials soft and pliable or water proof, and as lubricants. Pigments are used as dyes, fragrant oils for perfumes, essential oils for healing purposes.

We also use phytochemicals Bioactive chemical compounds found in plants. Many phytochemicals have medicinal properties, and others are important sources of vitamins. View Source Adapted from "phytochemical. Random House, Inc. Other unique materials, such as natural rubber are used in multiple commercial products. The biosphere also provides critical ecosystem services Natural processes by which the environment produces services and resources such as clean water and air, crops, timber, fisheries, pollination of native and agricultural plants, oxygen production, carbon dioxide uptake, decomposition of dead matter, soil stabilization, etc.

We often take for granted these and other ecosystem services provided by the biosphere, and yet they are critical to our existence on Earth. Check out this short video on deforestation threats , and learn more at the World Wildlife Fund website. Different types of ecosystems provide humans with different types of necessary resources.

They provide numerous natural resources to people as well, and are important in mitigating global climate change by sequestering great volumes of atmospheric carbon dioxide into their biomass. Deforestation The cutting down and removal of all or most of the trees in a forested area.

Deforestation can erode soils, contribute to desertification and the pollution of waterways, and decrease biodiversity through the destruction of habitat. View Source deforestation. Retrieved August 26 from deforestation. Deforestation and over-harvesting of forest organisms pose acute threats to biodiversity in many tropical regions including the Amazon, Indonesia, the Congo, and Sumatra Figure Figure Deforestation in Borneo, Malaysia.

The tropical rain forest is cut and burned to make way for access roads and terraces fields for palm oil production. In the upcoming Action Section you will learn about the IECA, an international organization which is addressing the global problem of soil erosion.

Around , square kilometers of tropical rain forest are lost each year to deforestation and over-harvesting. Removing trees at rates faster than the cycles of healthy re-growth reduces the biodiversity of these regions, which, in turn, threatens our food sources, sources of medicines, ecosystem services, and materials for building shelter. Today, clearcutting and slash-and-burn techniques expose the nutrient-poor soils to erosion by wind and rain, reducing the likelihood that the forests might recover.

View this video where rangers protect the endangered Irrawaddy Dolphins in the Mekong River between Cambodia and Laos from being caught in fishing nets. Aquatic ecosystems including oceans, wetlands, freshwater lakes, and rivers, are home to a high diversity of plants and animals which supply the major source of protein in the diets of billions of people each day.

In addition, millions of people worldwide make their livelihood from fishing the oceans, lakes, and rivers. Marine turtle bycatch. In addition to threatening many species of sea turtles and sea birds, the World Wildlife Fund estimates that , small whales, dolphins and porpoises become entangled in fishing nets that are set for other fish. These sea mammals die when caught in fish nets because they cannot surface for air.

The problem is one of complexity. There are several hundred, perhaps thousands, of potentially toxic chemicals for which every water sample could be analyzed.

Lakes, rivers, and groundwater all occupy three spatial dimensions that make representative samples expensive to obtain. Water quality also varies through time, so that recurrent sampling is required. And, finally, sampling in an extensive geographic area will probably reveal unsuspected links between various reservoirs. Three priorities have been established by the USGS: detecting major contaminated reaches of rivers; determining baselines in uncontaminated areas as benchmarks; and detecting groundwater contamination for those parts of the country where rivers or aquifers, or both, provide major water supplies.

Every human being requires about 2 liters of fresh water every day to maintain the minimal physiological functions. But many people use more than that amount; the added quantity varies according to an individual's personal habits and standard of living.

In North America every individual consumes or. This total includes the water that cools the turbines of power plants and the water that irrigates cotton fields, as well as the moisture that plumps the artichokes and provides the bulk of milk or muscatel.

It is the fluid that showers bodies and washes cars. It drips from faucets and drowns the roots of suburban lawns.

When it rains, this fluid runs in silken sheets along the slopes of parking lots and collects in open foundations at construction sites.

It gets pumped into the sewer system and mixed with organic waste and then runs out—to someplace downstream. As the population expands, and as material expectations rise, the need for water increases at an exponential rate. Over the past years, the amount of water removed from freshwater reservoirs by humans has increased more than fold. Most of the water used in North America does return to the hydrologic cycle after only a short interruption. The problem is that it frequently returns in a very different state and often to a very different reservoir.

If pure water is taken from a river and returns to the river contaminated by fecal matter or toxic materials, it may take long reaches of that river out of the supply side. And if vast quantities of water are mined from a ,year-old aquifer and run through an irrigation system, resulting in extensive evapotranspiration, the aquifer may not be replenished for another few hundred thousand years.

Because the hydrologic cycle transfers water from one reservoir to another at various rates and because it does not always transfer to the location most convenient for the schemes of civilized minds, humans must use available water resources very carefully.

Water cannot be manufactured economically from its component elements and ocean water cannot be desalinated without incurring large, usually unacceptable, expenses. So humans must adapt to the natural limitations on available fresh water imposed by the hydrologic cycle. In the United States the opportunity exists to deliberately formulate water distribution and wastewater treatment policies according to principles of conservation, wisdom, and justice.

The United States uses km 3 of fresh water every year. About km 3 is consumed—exposed for evapotranspiration or consigned to uses sequestered from the hydrologic cycle. The rest is recycled into the system as wastewater. Irrigation uses km 3 —41 percent of the total—and accounts for km 3 of the consumption. Domestic uses amount to 66 km 3 , consuming 20 km 3 ; and industry uses km 3 , but consumes only 29 km 3. Most of the river and lake water becomes available in the spring and early summer when the snow melts, ice breaks up, and rain falls to flush out—perhaps to flood—systems that run low in late summer.

Mitigation of droughts and prevention of floods traditionally require water control projects. Management of water supplies—circulating km 3 through U. In the half of the United States west of the th meridian—which slices through Texas, Oklahoma, Kansas, Nebraska, South and North Dakota—stream runoff is less than 1 inch in an average year.

Throughout that region runoff comes in early spring, largely as snowmelt from mountains hundreds of kilometers away. The water flows through the region months before the optimal time for watering crops. Storage of water—either in artificial surface reservoirs, lakes, or aquifers—dampens the lag in timing between supply and demand.

But no reservoirs create water; they only allow a delay of the transfer within the hydrologic cycle. Artificial reservoirs and lakes can be refilled when the runoff returns. Underground aquifers—the groundwater—serve as vast and wonderful reservoirs; but they often cannot be refilled in the next season.

Several western states now depend on mining underground aquifers—taking water out faster than the rate of recharge. In the past, official policy toward groundwater use endorsed the idea of safe yield. Safe yield was a concept accepted by hydrologists as a maxim—an aquifer should not be pumped faster than it is naturally recharged.

In the early s this idea was replaced by one that treated underground water as a nonrenewable resource: depletion of groundwater is justifiable if it creates an economy that can afford to buy more expensive water when the well runs dry. Adoption of this maxim reflects the development of irrigated agriculture in the High Plains as well as population migration to the Sunbelt. Now, urban and energy developments are coveting the water available to agriculture—especially in the Southwest.

This competition will undoubtedly intensify, posing two major issues for society: how local, state, and regional communities can manage increased competition for water and to what extent the country can wean itself from irrigated agriculture in the West.

The present domestic and industrial water requirements can be effectively met without serious impact on agriculture. Diverting 10 percent of current agricultural water consumption. But even without the competitive pressure from population centers, irrigated agriculture is in trouble. In the western states, irrigation accounts for more than 90 percent of consumptive use, and the surge in groundwater withdrawal over the past 25 years—since the philosophy of safe yield was rejected—has been due almost exclusively to irrigation.

In the conterminous United States, the 17 western states consume 84 percent of the country's fresh water, mostly for agriculture. The acreage irrigated in the 17 western states is shown in Figure 4. In Texas and California, which account for 42 percent of the total, almost one-half of this water is pumped from the ground.

Irrigation is also being increased in the more humid areas of the country to raise crop yield. Hydrologists calculate the volume of freshwater supply in terms of relative depletion.

Relative depletion is calculated from total consumption plus the total water exported from each drainage basin, divided by the total input of rain and snow.

The ratio is expressed as a percentage. Groundwater is not considered part of the total supply because it is not replaced by precipitation. The exclusion of groundwater from the calculation results in relative depletion that can exceed percent in some areas. Several regions in the United States are considered to be critically depleted; in most of the lower Colorado River basin, in Southern California, and in Nevada, depletion exceeds percent. These relative depletion figures are incomplete and probably low, because instream flow requirements are not included.

The instream flow requirement represents the minimum streamflow necessary to preserve aquatic and associated ecosystems. Maintenance of the instream flow is becoming an important constraint on water availability as the sensitivity of individual ecosystems is recognized. A familiar example is the case of Mono Lake in eastern California. Mono Lake is the last puddle left of an inland sea that has occupied the basin for more than 1 million years. During the most recent glaciation 12, years ago, the lake reached depths of m and extended over km 2.

In the course of postglacial warming, the lake level fell, but it has managed to maintain a rich variety of biotic systems thriving in its salty waters. In the city of Los Angeles— km to the south—began to divert the water that feeds Mono Lake. The lake's area decreased nearly 25 percent and its surface fell almost 20 m.

If the trend continues, there will be no ecosystem left in the lake: its instream flow requirement will not be met, and the lake will be too saline and too alkaline to support any life. A court decision has forced Los Angeles to stop diverting much of the water that normally would flow to Mono Lake, which may be sufficient to save the lake.

If not, it will share the fate of Owens Lake, which once glistened km to the south. All Los Angeles has left is the lake bed— km 2 of alkaline salt flats. The withdrawals from Owens and Mono lakes are only a fraction of the water exported to urban centers. In approximately 50 percent of the U. Efforts to eliminate the overdrafts of groundwater in Arizona have led to increasing dependence on surface supplies from remote locations.

The Central Arizona Project provides surface water to the Phoenix area from the Colorado River, over km to the west. Arizona has also implemented a new law to eliminate groundwater mining by the year California has eliminated relative depletion in the Central Valley by increasing surface water supplies.

Southern California continues to import 6. The city of Los Angeles alone extends its water delivery system over hundreds of miles throughout the Southwest and draws the power for the system from projects reaching across six states.

It has been involved in disputes over water with the state of Arizona and most recently with Mexico. But in California the cities use only 15 percent of all the water consumed. The rest goes to irrigation. In , 16 percent of the state's water supply irrigated fields of alfalfa, which is used to feed horses and cattle. That adds up to more water than is needed to supply 30 million people for a year. Difficult choices lie ahead for urban and rural Californians as droughts continue.

The southern High Plains represent an area of the United States that will return, sooner or later, to dry-land farming. The transition will come sooner and with fewer ecological and economic crises if the agricultural industry is weaned gradually from its dependence on groundwater irrigation.

If nothing is done until all the accessible water in the Ogallala aquifer has been removed, the transition will be ecologically dangerous and economically dreadful. Approximately two-thirds of this water is in Nebraska, which has an enormous reserve of groundwater and is nearest to the most productive recharge area.

In Texas and New Mexico more than 10 percent of the water initially in storage has been depleted. However, the depletion statistics for an aquifer such as the Ogallala are deceptively optimistic simply because it has not been economically feasible to remove all the water in underground storage because of the high cost of pumping from great depths.

It is estimated that 50 to 60 percent of the water might be removed under favorable economic conditions. Some areas in Texas and New Mexico have already reached the point at which irrigation from the Ogallala aquifer is no longer practical. In such areas of severe groundwater depletion, episodic surface runoff might serve for aquifer recharge if appropriate capture strategies were devised.

Humanity plays an integral role in the hydrologic cycle. While consuming less than 3 percent of the rainfall and returning large portions of that small percentage to the system, humans still profoundly disrupt the natural cycle. Human influence on our water resources is disproportionate to actual use because of the tendency to concentrate efforts in areas where the natural water supply is sparse.

The earliest irrigation was practiced in the deserts of the Middle East and was characterized by the same aims as today: to redistribute water geographically and seasonally—in space and time. Mesopotamians built canals and dams that would divert and delay the water flowing through the Tigris and Euphrates rivers. Early Egyptians worked to maintain the ponds and sluices that would trap the flood waters of the Nile and its rich silt. Both the water and the silt would be redistributed over fields at the proper time.

Water may have been a truly renewable resource in early history. Although monsoons and even the annual Nile flood might occasionally fail to take place, they always returned in a year or in seven.

But today hydrologic practices in some areas use water resources faster than they can be replaced. A lake impounded behind a dam may fill with sediment, although the chains of impoundment on many major rivers effectively reduce this risk. And ecological systems downstream of a dam may depend on the natural flood to flush pathogens. Rivers that flow into arctic waters maintain a cap of fresh warm water over the cold saline water that sinks to the bottom.

If stream flow were sapped from these systems, it could affect global ocean-atmosphereclimate links. Awareness of these and similar influences modifying the environment is growing at an astonishing rate, not just among scientists and engineers but in the world at large and especially among politicians.

Global change is a concept that has captured attention. Interest has focused on the changes that are likely to follow most directly from the burning of fossil fuel and the related increase in atmospheric carbon dioxide. Human involvement in modifying the hydrologic cycle has received limited attention as an aspect of global change, but the obvious can no longer be ignored.

In the past years human endeavor has destroyed natural streamflow patterns by damming up most of the major rivers of the Northern Hemisphere. Aquifers in arid and semiarid areas have been mined to dangerous levels. Water quality has deteriorated because of the disposal of wastes in streams, lakes, and aquifers, and water salinity has increased in critical areas as a result of irrigation practices.

The dissolved salt and the organism components of groundwater are receiving more attention with the recent recognition that irreversible changes are occurring in important aquifers. They are being contaminated by sewage and also by seawater. When fresh water is removed too quickly from groundwater reservoirs along coastal plains, the spaces fill with saltwater. Because of such saltwater intrusions, the cities of Miami, Pensacola, Daytona Beach, Brooklyn, and Los Angeles have had to abandon important aquifers.

Impoundment of a major reservoir behind an artificial dam illustrates how human-induced change affects the hydrologic environment which in turn propagates through the earth system. Impoundment of Lake Nasser by the Aswan Dam was expected to change agricultural practices downstream that had responded to the annual Nile flood for thousands of years.

However, the generation of earthquakes caused by the load of the lake on the lithosphere was not considered, nor was the higher elevation of water levels in the Nubian sandstone beneath the desert on either side of the lake. Neither did anyone expect an epidemic spread by snails that had formerly been flushed from the marshy river banks with the annual flood or depletion of the soil and incursion of the Mediterranean and loss of fisheries into the delta region because sediment supply had been cut off.

On the other hand, rising water levels in the Nubian sandstone have made water wells more productive over a large area. The drought and famine in Ethiopia and neighboring countries upstream from Aswan have not affected Egypt because of the availability of irrigation water from Aswan. The dam has also prevented several dangerous floods.

Humanity can learn from its mistakes. If so, one of its major goals will be that of understanding the complex earth systems well enough to predict the possible consequences of ongoing changes.

In the field of hydrogeology, a variety of crises have stimulated accelerated studies and actions, especially an improved understanding of groundwater flow. But many aspects of our water resources remain undefined or even unrecognized. The geoscientist's role is to understand and synthesize the multiple factors involved in the maintenance of adequate water resources so that policy makers—regionally, nationally, and internationally—can reach informed decisions.

The demands of that role represent a remarkable opportunity for newly integrated studies of the hydrologic cycle and particularly for the application of new observational, analytical, and modeling approaches to understanding the groundwater system. The word mineral can be defined in a variety of ways. One definition includes any naturally occurring substance that is not a vegetable or an animal.

The geoscientist defines minerals as all the naturally occurring solids—plus a few liquids—that display distinctive chemical composition and crystalline structure and that are the components of rocks. To the economist, minerals are materials extracted from the Earth that have current or potential economic worth, and any site from which such material can be recovered is considered a mineral deposit.

For this section the most appropriate definition includes economically valuable material that is not considered mineral in the strict geological sense, such as the synthetic open-framework silicates—the types of zeolites that are used as molecular sieves. Mineral resources include the naturally occurring combinations of elements, the ores that contain. Understanding the location of metallic ores and how to mine them is one of the most ancient fields of geoscientific endeavor. Research involving mineral deposits is similar in some ways to research in oil and gas exploration.

Both are strongly affected by economic fluctuations and international politics. When the industries thrive, the larger companies manage extensive research programs that foster close links between exploration projects and scientists from government and universities.

At the same time, smaller enterprises can justify ventures that would be considered too risky in a sluggish market. Advances in geophysics, geochemistry, and data-gathering and data-handling capabilities have revolutionized mineral exploration and development, as they have the petroleum industry. Both industries are especially stimulated by applications of new theoretical concepts. Mineral resources are generally concentrations, sometimes exceptionally high concentrations, of one or more of the materials that constitute the solid-earth.

Ninety-nine percent of the crust is made up of only nine chemical elements: oxygen, silicon, aluminum, magnesium, iron, calcium, sodium, potassium, and titanium. It is the other 1 percent of the crust that captures the interest of the mineral exploration geoscientist who wants to know how, when, and especially where concentrations of minerals occur.

Interest centers on understanding the processes that form the mineral deposits, the environments in which those processes operate, and the distribution of deposits through space and time. From this understanding, new deposits can be predicted, discovered, and developed, and existing ones can be exploited efficiently.

Mineral deposits form through a wide range of geological processes that may operate at uncommon levels of effectiveness or in unusual associations. In some situations, rocks such as sandstone and limestone qualify as mineral deposits because they are of economic value in a particular place.

Sands and gravel deposited in the bed of a mountain stream provide a simple example of such a situation. Where a stream erodes crustal rocks that contain gold, the downstream gravels may contain anomalously high concentrations of the precious metal. This is because the weathered gold particles are denser than the gravels and sands.

The stream deposits the gold particles when it loses the capacity to carry particles of that density and size, so the gold accumulates within a particular reach of the stream. These are the placer deposits that have been the sites of gold mining throughout history, from the mythical deposits of Colchis where Jason found the Golden Fleece to those of Sutter's Mill in California that inspired the forty-niners of a century and a half ago.

Less than one part in 10, of the metals present in the upper kilometer of the continental crust is concentrated in known mineral deposits. The remainder is widely dispersed at low concentration and, for that reason, is unsuited to economical recovery. Ore deposits are rare indeed! A simple illustrative plot for the metal lead shows how concentration of a typical element varies in the crust Figure 4. The range of concentrations is so large that it is necessary to represent it logarithmically.

Common crustal rocks contain about one part in , of lead by weight; this is represented by the crest of the bell-shaped curve. There are virtually no rocks in which the amount of lead is too small to be measured. The smooth curve represents the gradual increase in lead abundance, with the maximum representing the most probable value for a randomly selected sample. The fall in abundance from this value is not symmetrical. Economically workable lead concentrations—rocks with a lead context of more than a few percent—occupy a place at the far right end of the curve.

Deposits with lower lead content are expected to become economically profitable at some time in the future when all larger deposits are exhausted. A threshold identified as the mineralogical limit separates a deposit in which rocks contain lead-dominant minerals from a deposit of lead so evenly distributed through the rock that it does not form discrete mineral concentrations. Although by definition all lead ores fall within the first category, there is a far greater total amount of lead distributed thinly throughout crustal rocks.

Lead is just one example of crustal element occurrence that can generate a bell-shaped distribution curve. Such distribution patterns indicate the challenge of mineral exploration, which is to discover the small amounts of concentrated materials constituting ore bodies. These concentrations not only are rare but can be extraordinarily localized.

For example, seven gold fields covering an area of about 5, km 2 —no larger than the county of Los Angeles—within the Witwatersrand basin of South Africa have produced more gold than has been discovered over the remainder of the surface. The mercury deposit at Almaden, Spain, has yielded more mercury than any other source and still retains the bulk of the world's reserves. The Bushveld intrusion in South Africa contains 98 percent of the world's chromium reserves, most of them in a single layer.

These are unusual concentrations of gold, mercury, and chromium, but researchers question whether they are unique. Such rich deposits represent only minuscule proportions of otherwise ordinary parts of the crust. The possibility exists that similar deposits are hidden in the unexposed basement rocks of the North American mid-continent, beneath the jungles of South America or Southeast Asia, or under thin cloaks of glacial drift in Canada.

While exploration has the potential to be a very prosperous undertaking, success in a venture characterized by cryptic clues and expensive tests requires steadily increasing levels of understanding about deposits and their environments. To illustrate the fact that new sources of strategic minerals continue to be discovered, consider two commodity sources that once were thought to be unique but have proven otherwise: the Climax molybdenum deposit and Southeast Asian tin.

The Climax molybdenum deposit at Fremont Pass, Colorado, was for half a century the overwhelmingly predominant source of molybdenum—used in the steel industry—although by-product molybdenum was also recovered in significant amounts from some copper deposits. Despite a ready market, other major molybdenum deposits were not identified until the s, when the essential geological characteristics of the Climax deposit were recognized in numerous other localities. The result was that a series of major molybdenum deposits was discovered and brought into production.

Similarly, the marine placer deposits of Southeast Asia dominated the world tin market for years, because they could provide tin more cheaply than any other source.

However, in the s the world tin market collapsed, and many Southeast Asian operations were sharply curtailed when abundant low-cost tin emerged from the Rondonia district of Brazil.