Earths Structure & Solid Waste
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Unraveling the mysteries of the Earth’s geophysical processes is one of the most exciting scientific adventures of this era. At the same time, understanding geophysical processes has a practical significance that goes beyond scientific curiosity.
Geophysical processes result in the building of mountains, the eruption of volcanoes, and associated earthquakes. Other physical and biological processes interacting with geophysical processes act to wear away mountains and form the soil in which plants grow. The results of all these interactions determine whether a place is suitable or hazardous for life.
Geophysical processes should not be considered in isolation. Weathering of rocks, for example, must be examined in the context of atmospheric, hydrologic, and ecologic systems. People also interact with the geophysical environment and through imprudent or thoughtless actions have at times precipitated geological events with wide-scale, sometimes disastrous results, such as landslides or subsidence of the land. Because of the scale, magnitude, and power involved, the possibility of ever being able to control geological systems completely is only a distant vision. Knowledge and understanding of these processes, however, can be applied so that cities and homes are not built in hazardous locations, construction is suited to the geology, habitats for people and animals are preserved, and the resources of the earth are used to enhance the quality of human life. Since geophysical systems form the basis for planned land use and intelligent environmental management, selected aspects of geology which affect habitats or illustrate the effects of people on geological processes are presented as basic influences on all life.
Natural processes that result in changes in the earth’s climate or vegetation occur over thousands or millions of years. These changes are recorded in the sediments and rocks of the earth. To unravel this history, we must establish dates of events that have occurred over millions of years.
Developments in atomic physics in this century have been a boon to individuals trying to establish reference points in geologic time. The technique used is based on the fact that some elements are not stable, that is, they readily disintegrate and in the process emit particles and energy. The process is called radioactive decay and such elements are said to be radioactive. In the process of disintegration, the unstable element will take on the characteristics of a different element, which in turn may also decay. This process continues until a stable element is formed.
The rate of decay is different for each element, but is constant for each radioactive element. The rate is measured by the length of time it takes one-half of the atoms present to disintegrate—the half-life. If an element has a half-life of 100 years, one-half remains after the first 100 years of decay. One-half of that, or one-fourth of the original material, will remain after 200 years. One-eighth remains after 300 years, and so on. Some radioactive elements have a half-life of seconds; others, thousands of years.
When a rock solidifies from a molten state, radioactive elements may be locked in. If the rock remains intact, the decay products from a period of years, including the final stable element, are retained in the rock. If you knew the amount of a particular radioactive material in the rock at the beginning and the amount now remaining, it would be possible to estimate its age from the established rate of decay. In cases where we do not know the amount present in the beginning, the initial amount is estimated from the ratio between the amounts of unstable radioactive element remaining and the stable end-product element. These computations indicate the age of the rock since it solidified.
There are several radioactive chains that are used to date rocks, including some which start with uranium and end with lead. Some rocks have been found that have been dated at 3.5 billion years old. The age of the earth is estimated at between 4 and 5 billion years. A similar process using radioactive carbon is used to date plants and other organic material younger than 30,000 years.
Another method that can be used in conjunction with radioactive dating is based on the magnetic orientation of beds of rock. Molten rock becomes magnetized and is oriented to the north and south poles as it solidifies. For some unknown reason, the polarity the location of the north and south poles of the earth has periodically reversed through time and these magnetic reversals are reflected in the magnetic orientation of the rock. This phenomenon can be used to determine which rocks on both the ocean floor and on land were formed at the same time.
The relative position of a rock layer among other layers also helps in dating. Normally the upper layers would be the youngest (that is, the most recently deposited); however, patterns of deposition are often complex, and local geological formations have to be examined carefully to determine whether the deposits have been disturbed or if layers have been removed by erosion. Plant and animal remains may also be incorporated into sediment layers as fossils and can provide additional clues about an area’s age and history.
The earth went through a molten period in its formation about 5 billion years ago. During the molten period, the heavier materials settled toward the center of the earth to form the core and the lighter materials floated on them to form the crust. The core is in two layers: a solid inner core and a liquid outer core. The crust (lithosphere) is solidified material, but lighter than the core.
The rock (basalt) forming the ocean floors and found underneath the continents is heavier than the granite rocks that form the continents. This difference in density is an important factor in the floating of continents on large segments of crust, called crustal plates, which move and carry the continents along. Like a ship that rides high or low in the water according to how heavily it is loaded, continents protrude downward underneath mountains in proportion to the height of the mountain. Thus, the rock layer is relatively thin in lowland areas and thicker where there are mountains. As mountains wear away, the depressed material rises. Similarly, land depressed by the weight of ice rebounds when ice melts. The principle involved is called isostasy.
To help reconstruct the sequence of past geological events, we have fixed the approximate times for the formation of rocks and the deposit of sediments. Theories about the spreading of the sea floor and the movement of continents have evolved from these data. An understanding of past events and when they occurred is also valuable in locating deposits of ores, oil and gas. When coupled with fossil records, geophysical events which led to the expansion or decline of ecosystems may be understood.
We accept that the earth is moving through space,
but only recently have we recognized that the continents are moving on the
surface of the globe. This recognition came about as a result of observations
of scientists over many years. Scientists noted the similarity of certain
species in areas of the world that are now remote from one another traced the
appearance. For example, South America, Africa, and
Many people have looked at maps of the world and
noticed the similarity of the coastline of western Africa and eastern
By using the magnetic orientation of undisturbed
molten rock masses, tectonic data such as old mountain belts, sedimentary
deposits, fossils, and climate history, scientists have speculated about the formation
of continents and how they have moved about. Evidence exists of movement for
2,500 million years. About 330 million years ago, the existing continents
converged to form a single landmass - Pangea. After Pangea broke into two super continents some 200 million
years ago, periodic divisions and collisions have occurred causing the opening
and closing of ocean basins. Pangea was surrounded by
the universal ocean Panthalessa—the ancestor of the
present Pacific. A sea, the Tethys, intruded between
While the Pacific is an ancestral ocean (the
remainder of Panthalessa), the
There are now ten major plates and a few
sub-plates in the world. A plate that moves over 3 centimeters (1.2 inches) per
year is considered to move fast. Some 80 million years ago the plate carrying
The Pacific plate is presently being consumed at a
rate of 8 centimeters (3.1 inches) per year—a rate which will require
replacement of its 15,000-kilometer width in 100 million years. One of the
slowest current rates of sea floor spreading is in the
Moving and colliding continents are responsible for
major landforms of the
continental movement directly involving
portions of the
Volcanoes And Earthquakes
Improved knowledge of the more threatening aspects of volcanoes and earthquakes can be useful in avoiding catastrophes. In time, slippage along transform faults might be managed so that severe earthquakes resulting from sudden slippage could be avoided. Greater accuracy in predicting impending volcanic activity and plate movements will allow for early warning. This information could also be utilized in land use planning to avoid natural hazards, especially in locating sensitive facilities such as dams and atomic energy plants. Building codes could be specially adapted for construction in earthquake-prone areas. Millions of dollars in property damage could be averted and thousands of lives saved by knowledge we now have.
Volcanoes are especially dramatic natural hazards, to which human responses are determined by several factors, including the size, intensity, and frequency of eruptions. We will compare two very different types of volcanoes, volcanoes found near subduction zones and volcanoes associated with oceanic hot-spots.
A hotspot is a pool of molten rock in the upper
mantle. As a plate moves across it, the molten material may erupt through the
plate, producing a volcano.
Hotspots that occur under the ocean floor produce volcanic islands. As the sea floor plate
moves, old volcanoes lose contact
with the hot-spot and become extinct, but this allows for the formation of new
volcanoes. The trail of extinct volcanoes is exemplified by the chain of
islands and seamounts (a submerged, extinct volcano) in the Pacific that
includes Midway and
Volcanoes form at subduction zones when the
descending plate melts and some of the molten material finds its way through
fissures back to the surface. It is common to have an arc of volcanic islands,
a rim of fire, just beyond the subduction zone formed by these deep-rooted
volcanoes, such as the islands of
We live in a dynamic world where conditions are forever changing and the understanding the dynamics of geophysical systems can aid in the search for minerals and petroleum deposits. By recognizing the conditions that led to a particular deposit on one continent, prospectors can look for a similar deposit or vein on another continent that may have been connected to the first. Furthermore, with the aid of satellite pictures, prospectors can predict where to look on the other continent.
The deposit of sediments heavily laden with organic
matter in shallow marine areas adjacent to continents favors the formation of
oil. Therefore, in the early formation of the
The non-recyclable solid wastes of urban societies could be dumped or placed in the subduction zones, to be carried into the mantle. While toxic materials not readily degraded might be disposed of in this manner, it is not necessarily a practical solution for the disposal of nuclear wastes for several reasons. The nuclear material could be scraped off as the sea floor crustal plate descended into the mantle at the subduction zone, to be uplifted later rather than descending into the mantle with the plate. Or, the nuclear waste might find its way back to the surface through a volcano originating in the subduction zone.
Over a longer period of time, plate tectonics
explains the raising of mountains and the movement of continents. These events
produce dramatic changes in weather and climate, the effects of which
ultimately influence the vitality of ecosystems and the evolution of various
species of life. Imagine the change in vegetation that will occur as
Minerals and Ores
All substances are composed of chemical elements. Ninety-two elements are known to occur in nature, and ten of them constitute 99 percent of the earth’s crust. The basic units of elements are atoms, and two or more atoms may be joined together to form molecules.
Molecules may be made by joining two or more atoms of the same element. For example, an oxygen molecule is composed of two atoms of the same element—oxygen. Three atoms of oxygen produce a molecule of ozone. Many molecules, however, are made of different elements. A molecule of table salt, for example, has one atom of sodium and one of chlorine. We call large quantities of like molecules chemical compounds. For convenience, a type of international shorthand notation using letters to represent the chemical element (such as 0 for oxygen, Na for sodium, and Cl for chlorine) is used to describe the composition of compounds.
Average Composition of the Earth’s Crust.
The symbolic letters are not necessarily related to the English word for the element, but frequently are derived from some other name. To indicate the number of atoms of an element in a molecule or a chemical compound, that number is placed as a subscript immediately after the letters. Therefore, oxygen is 02, ozone is 03, and table salt is NaCl.
Water is the closest thing in nature to the mythical universal solvent. Whether or not a rock dissolves readily in water determines how rapidly it weathers. When substances are dissolved, some of the atoms, or groups of atoms, dissociate in the liquid into what are called ions. The ions have positive or negative electrical charges. Thus, salt (NaCl) when dissolved will produce a sodium ion (written Na+) and a chlorine ion (Cl-).
If an excess of hydrogen ions is present, the liquid is acidic; and if hydroxyl ions are in excess, it is basic or caustic. An index scale based on the relative number of hydrogen ions present has been developed to represent this relationship. Called a pH scale, it uses numbers from 0 to 14. A pH of 7 represents a neutral condition, where the hydrogen and hydroxyl ions are balanced.
Chemical interactions have applications in many environmental and life systems for example limestone readily dissolves in water to form solution channels and caverns. Gold, on the other hand, ionizes very little and can be recovered (usually in very small amounts) from sediments in streams.
Rocks are mixtures of substances called minerals. About 90 percent of all minerals occur as ionic type compounds and therefore do not consist of molecules in the usual sense. The mineral names are different from the names of chemical compounds, as in the case of calcite and calcium carbonate. Limestone rock is composed of one atom of calcium (Ca), one atom of carbon (C), and three oxygen (O3), plus impurities. The chemical compound of that composition is known as calcium carbonate (CaCO3) by chemists, but mineralogists have given the name calcite to rocks of that composition. As a result of leaching, deposition, chemical action, reaction to temperature, and other prevailing factors, certain minerals occur in great abundance in deposits or veins, sometimes known as ores. The term ore is used to indicate that it is economically profitable to extract the mineral.
To understand geologic processes, we must be familiar with three rock types. Igneous rocks are formed by the cooling of molten material. The upwelling of molten material at ocean rifts forms rocks called basalt. The melting of continental debris carried into subduction zones with the plates and of continental rocks down folded where plates bump into each other creates granite rocks.
As mountains wear away, rock
fragments are transported and deposited in various locations in layers that are
usually flat or gently sloping. This loose material is subsequently
consolidated by pressure or cemented together in a process called lithification to form sedimentary rocks. Often, large-scale
earth up-heavals accompanying volcanic action, the
collision of continents, and eqarthquakes tilt and
fold these layers. When rocks are subjected to extremely high pressures and to
temperatures short of melting, their physical and chemical characters are
changed and they become metamorphic rocks. Limestone is a sedimentary rock, and
marble is the corresponding metamorphic rock derived from limestone. This
process of forming one rock out of another is called the "Rock
This process of forming one rock out of another is called the "Rock Cycle".
Rocks begin disintegrating upon exposure to wind, sun, and rain. How fast the weathering proceeds depends on the type of rock, its mineral composition, and the chemical and physical weathering processes to which the rock is subjected. In general, igneous rocks are the most resistant and sedimentary rocks the least resistant to physical weathering. Temperature changes make rocks expand and contract, causing fractures. Water enters the cracks and freezes, with the expansion of the freezing water breaking up the rock further. Roots entering cracks can also break rocks apart as they grow and enlarge. When pieces of rock are moved by slides, wind action, rivers, and glaciers, the rubbing action of one rock against another (abrasion) results in even smaller fragments.
Disintegration and weathering of rocks reduces particle size and releases inorganic nutrients in rocks, resulting in deposits of unconsolidated material from which soil is developed. The uppermost layer of soil, topsoil, is composed of small rock fragments, sand and silt, the remains of plants and trees, and live soil organisms. Clay is a product of the disintegration of granite rock and is mixed with the sand and silt. Rain percolating through the topsoil removes (or leaches) the soluble materials like calcium carbonate and iron oxides and deposits them in the subsoil below. Beneath the topsoil and subsoil is a transition zone to the unaltered base rocks or sediments which contains a mixture of base rock fragments and subsoil.
The topsoil is the living portion of the soil that is important to the growth of trees and other vegetation. The decaying remains of trees, plants, and other organic material is called humus. In addition to supplying organic nutrients to the soil, humus retains moisture and provides spaces for oxygen to reach the roots of growing plants. It takes ages to develop the topsoil, but only one generation to destroy it by human action. Naturally destructive processes are accelerated by removing trees, careless plowing, and failing to rotate crops and replenish the natural humus.
The general processes whereby crustal material is worn away and removed by weathering, solution, abrasion, and transportation is called erosion. In the process of erosion, the force of gravity acts on loosened rock and soil to restore upraised land to a base level. Water aids the process by transporting and depositing material downhill. The process of topsoil erosion begins with the splatter of the first raindrop. (In areas unprotected by vegetation and especially in arid areas, wind may cause erosion.) Rain which does not seep into the ground forms tiny rivulets that carry material downhill to be washed away by rivers. Ground cover, topography, and other factors influence the rate of erosion. When the ground is saturated with water, the angle of repose is usually much less than if the ground were dries. Earthquakes increase the pressure on the ground, causing an effect similar to saturation of the ground with water - liquefaction.
Landslides occur naturally where rivers eat away at
the toe of a hill. The bulldozing of terraces in hillsides for home
construction and making deep cuts for highways and similar activities cause
many slopes to fail. Not only have slides been caused on the upper side of a
terrace or highway by undercutting the slope, but slides on the lower side of
the cut have been caused by piling up earth at an angle exceeding the natural
angle of repose. In the
Other types of massive earth movements include debris slides, mudflows, and earth flows. Mudflows originate in small, steep canyons. Debris at the bottom of the canyon mixes with flood waters and moves down the canyon as a sloppy mass of mud and debris. Where mudflows occur periodically, the material accumulates at the mouth of canyons in cone shaped deposits called alluvial fans.
Earth flows result in areas where freezing pushes material up and away from the hillside. Upon thawing, the ground falls back into place slightly downhill. Repeated cycles result in the surface earth creeping downhill almost imperceptibly. Creep is especially troublesome in efforts to stabilize fresh highway cuts, where roots of grass do not penetrate to a sufficient depth to hold the earth in place. Employing deeper rooted vegetation that can reach below the depth of frost upheaval or artificial means may be helpful in stabilizing the banks.
Withdrawal of water from the ground faster than it
is replenished by rain lowers the water table. Removal of the water allows the
ground to be compacted by the weight of the material above, resulting in a
settling or subsidence of the ground surface. In
A similar subsidence results from pumping oil and
removing natural gas from the ground. In the 1920s, the
Subsurface mining of
ores, coal, sulfur, and salt may remove support for the overlying material and
result in collapse of the surface. In 1963 an auto disappeared in a ground
collapse in Wilkes Barre,
Solid waste is useless, unwanted, and
discarded material lacking sufficient liquid content to be free-flowing. More
than 10 billion tons of solid waste is generated each year in the United States,
most of it from agricultural activities. This waste is primarily produced by
farm animals, slaughterhouses, and crop harvesting. The mining industry is
another major producer of solid waste, generating over 2 billion tons a year.
Its solid waste comes from the extraction, beneficiation (preparation for
smelting), and processing of ores and minerals. But residential and commercial
wastes are probably more familiar to the average person. These include
everything from plastic bottles, aluminum cans, and rubber tires to yard
trimmings, food wastes, and discarded appliances.
Of the municipal Solid Waste in
Hazardous waste is legally defined as
discarded liquid or solid that contains: one or more of 39 toxic compounds, is flammable, explosive, and can release toxic fumes or
corrosive to metal. Congress exempted from the hazardous waste list many toxic
categories in order to save industries and government money. Only 6% of hazardous waste produced in the
Waste management is a high waste viewpoint which views waste as a necessary product of economic growth. Waste is burned, buried, or exported to another place. Low waste viewpoint views waste as a recyclable, compostable or reusable resource or as harmful substances we should not be using. This approach reduces input of matter and energy resources and puts outputs back as resource inputs. The high waste approach increases input of matter and energy resources through the economy.
In a low-waste approach 60-80% of solid and hazardous waste could be reduced, reused or recycled. The remaining 20-40% of wastes could be treated chemically or biologically to reduce their toxicity and burn or bury what is left. Currently the United Stated and most countries do not include production and handling of waste in the market price of products so waste is burned, buried or exported.
Reducing waste and pollution can be good for corporate profits, worker health and safety, the local community, consumers and the environment. Being a "Green Company" is being supported by quality of life communities, selective stock investors and contentious consumers. Most waste reduction initiatives have shown no capital investment or are paid back in 6 month to 3 years.
Waste and pollution can be prevented by:
redesign manufacturing processes and products to use less material
design products to use less energy and produce less pollution .
manufacturing processes redesigned to produce less pollution and waste .
use cheaper and less hazardous cleaning products .
develop products that last longer and are easy to repair, reuse, remanufacture, compost or recycle
eliminate or reduce unnecessary packaging .
trash taxes to reduce waste
For years the question has been "Where should we put toxins and solid wastes?" We should be asking "Why are we producing this waste?" This question leads to pollution prevention and waste reduction rather than pollution control and waste management. The real question one needs to explore is who is benefiting from waste production and who pays the cost? When you know both sides of the issue, you can decide what you want to do, be part of the problem or be part of the solution.
Lois Marie Gibbs, Citizen's Cleaning House for Hazardous Waste believes reuse of containers should be encouraged, bottle deposit laws have been very successful. However in some areas collection and return of bottles have been dismantled. If one has a choice they should choose glass, then aluminum and last plastic containers. Glass can be used, aluminum can be recycles and the plastic is limited by the type (PET) of plastic hydrocarbons used as to whether it can be recycled. Used tires should not be discarded or put in land fills. They can be reused, recycled or burned for energy (under strict air pollution controls).
There are two types of recycling: primary, closed-loop where waste discarded by consumer is recycled to produce new same type of product. (automobiles into automobiles, newspaper into newspaper) secondary or open-loop recycling in which the wastes are converted into different products.
Primary recycling reduces virgin materials in a product by 20-90%. Secondary recycling reduces virgin material use by 25% at best. Anything can be labeled recyclable but one should choose the maximum post consumer content.
Large scale recycling can use mixed urban
waste and transport it to a centralized materials recovery facility where
machines separate and shred wastes.
Resources are recovered and sold as raw materials. Remaining waste is recycled or
incinerated. It takes a lot of money and energy to separate
garbage resources. Incineration may
produce toxic ash which must be properly disposed. Increased truck traffic, odor, noise and
poorly designed plants make these mixed solid waste
difficult to maintain.
Many solid waste experts say it is economically and environmentally advantageous to separate household and business trash into recyclable and reusable categories before it is picked up. Source separation produces little air, water pollution, reduces litter, have low start up costs and moderate operating costs. It saves more energy and provides more jobs. It creates 3 to 6 times more jobs than land-filling or incineration. Source separation educates people about the need for waste reduction, reuse and recycling.
Recycling programs should not be judged by whether they pay for themselves but rather for the reduction of virgin resources, reduced energy and material input and reduced pollution and environmental degradation. The reason there is not more reuse and recycling is due to several factors: consumer items do not include environmental costs of raw materials.
Plastics are difficult to recycle due to many resin types. Plastic manufacturing is a leading producer of hazardous waste. In landfills toxic cadmium and lead leach out of plastics and enter the groundwater and surface waters. Currently plastic petrochemicals costs are so low that virgin plastic resins except for PET are about 40% lower than recycled resins. Plastics are durable and some can be reused however single-use packaging and throw away beverage and food containers should be reduced and replaced with less harmful and wasteful alternatives.
Bioremediation can clean up toxic and hazardous waste. More than 1000 species of bacteria and fungi are being used to clean up pollution. Phyto-remediation using natural and genetically engineering plants are used to remove contaminants such as lead and mercury. Incineration of hazardous or solid waste released toxic air pollutants. Toxic lead and mercury can not be removed by scrubbers as well as dioxins which eventually will leach from the toxic land and field.
Sanitary landfill are
used for 60% of municipal solid waste in the
Solid-waste landfills have
disadvantages. They cause traffic
congestion, noise, odors and organic breakdown is very slow in the water-oxygen
deficiency landfill. Methane is generated and collected with vent pipes.
Eighty-six percent of landfills studied in the
Most hazardous wastes in
In 1994, 64 nations signed a ban on all
exports of hazardous materials from developed countries into developing
To prevent pollution and reduce waste, one needs to live by these principles:
1. everything is connected
2. there is no "away" for wastes
3. dilution is not the solution for most waste
4. the best and cheapest way to deal with waste is to produce less waste and to reuse and recycle most materials we use.
Examples of Non-hazardous Waste
Aluminum, glass, and plastic food/beverage cans and bottles and aluminum foil
Cardboard and paperboard (for example, cereal boxes and manila folders)
Mixed paper or various paper types (white, glossy, and colored papers, including soft- and hard-covered books, magazines, newspaper, telephone books, junk mail, computer printouts)
Styrofoam packing beads
Computer floppy disks and compact disks
Laser and inkjet printer toner cartridges
Wooden pallets, spools, and scrap wood
Examples of Hazardous Wastes
ACIDS - Boric Acid,, Muriatic Acid, Metal Cleaners, Ferric Chloride, Hydrochloric Acid, Disinfectants, Mercury, Car Battery Acid, Phosphoric Acid, Pool Acid, Sodium Bisulfate, Copper Sulfate, Rock Salt
BASES, CYANIDES - Ammonia-Based Cleaners, Battery Terminal Cleaner, Caustic Soda, Sodium Hydroxide, Drain Cleaners, Lye, Oven Cleaners, Cesspool Cleaners
ORGANICS (NON-FLAMMABLES) - Moth Crystals Pruning Paint, Brake Fluid, Cutting Oil, Duplicator Fluid, Formaldehyde Solution, Grease, Paraffin Oil, Roofing Cement, WD-40, Pharmaceuticals, Asphalt Driveway Topping, Creosote, Dap, Floor/Furniture Polish, Formalin, Liquid Waxes, Power Steering Fluid, Tire Black, Wood/Tile Putty
FLAMMABLES - Acetone, Automotive Body Filler, Diesel Fuel, Ethanol, Engine Starting Fluid, Gasoline, Kerosene, Liquid Sandpaper, Naphtha, Plastic Model Cement, Toluene /Totuol, Xylol/Xylene, Alcohols, Barbecue Lighter Fluid, Denatured Alcohol, Ether, Fingernail Polish :Remover, Isopropyl Alcohol, Lighter Fluid, Methanol, Perfume, Polyurethane Cement, White Gas
OXIDIZERS - Ammonium Nitrate, Caldium Hypochlorite, Fertilizers (Nitrogen-Base), Hair Coloring, Hydrogen Peroxide, Nitric Acid, Potassium Permanganate, Toilet Cleaner with Bleach, Bleach, hlorates, Fluorine, Hair Dye, Iodine, Peroxides, Sodium Hypochlorite, Stump Killer
PESTICIDES - Ant and Roach Killer, Black Flag, DDT, Dog Repellant, Flea Spray/Powder: Gopher Killer, Lindane, Mole Killer, Pyrethrins, Raid, Round-Up, Snail/Slug Killer, Baygon, Chlordane; Diasinon, Dursban, Fungicides, Insect Sprays, Malathion, 'OFF' Insect Repellant, Strychnine, Rose Dust, Sevin
PAINTS - Thinners, Lacquer, Turpentine, Primers, Epoxy Paint, Shellac Thinner, Varnish, Oil Base Paint, Solvent Base Paint, Shellac, Wood Stain, Linseed Oil, Varathane
ORGANIC SOLVENTS - 1, 1, 1-Trichlorethane, Methylene Chloride, Degreasing Solvent, Perchlorethylene, Carbon Tetrachloride, Carburetor Cleaner
Summary And Conclusion
Understanding the physical systems of the earth is essential to intelligent land use planning. The physical systems with the atmospheric and hydrological systems influence as well as being influenced by human activities.
Our description of the earth’s physical systems began with the powerful, slow, but relentless forces deep within the earth. The earth’s crust is torn apart into plates that are moved about, renewed by molten rock rising to fill the rift, and ultimately consumed where one plate collides with another and is diverted underneath to sink back into the mantle. Continents are torn asunder, volcanoes born, and mountains raised in the process. Other forces such as wind and rain, freezing and thawing erode the mountains and develop the soil in which plants grow to nourish life. These phenomena need to be carefully considered in the location of human settlements in order to avoid or minimize the effects of such natural hazards as volcanoes, earthquakes, landslides, and subsidence. Some human activities disturb the ground, accelerating erosion or inducing landslides; the extraction of water, oil, and minerals in ways that precipitate subsidence of the ground surface; and the development of coastal areas interfering with ecosystems accelerating natural processes that are detrimental to natural ecosystems and the quality of human life.
This information can be used for rational land use planning in order to plan for future extraction of minerals and building materials such as stone, sand, gravel, and clay; to avoid land development in geologically hazardous areas; and to protect environmentally sensitive areas.