Sabtu, 18 April 2009

The Ultimate Goal of Ecology

(Wed Dec 24th, 2008, by Dr.Badruddin Khan)

Ecology is the study of the relationships of organisms with their living and nonliving environment. No organism exists entirely independently of other living and nonliving things around it. A cactus in the middle of the desert, for example, draws nourishment from the air and from the ground and depends on sunlight for energy needed to grow. The cactus may be home to birds, lizards, and microscopic animals. Even relationships that seem to be stark and simple as that of the cactus with its surroundings involve complex ties that form the subject matter of ecology.

Ecological relationships are always reciprocal (shared) relationships. In the example of the cactus, elements of the physical environment, such as air and water, have an impact on the cactus. But, at the same time, the cactus affects its physical surroundings. For example, it releases water vapor and oxygen into the air, changing the composition of the surrounding atmosphere. Living relationships are also reciprocal relationships. The cactus may provide food, shelter, and shade for animals that live in or near it. But animals also contribute to the life of the cactus, by distributing its seeds, for example.

Although mostly a biological subject, ecology also draws upon other sciences, including chemistry, physics, geology, earth science, mathematics, computer science, and others. As the impact of humans on the environment increases, the subject matter of ecology expands. Ecologists may be asked to decide whether a desert should be left in its natural state or opened to certain forms of human development. As a result, ecologists increasingly find themselves confronted with social, economic, political, and other nonscientific issues. Because it draws upon knowledge and information from so many disciplines, ecology is a highly interdisciplinary field.

That ecologists focus on biological subjects is apparent from the fact that most ecologists spend much of their time engaged in studies of organisms. Examples of common themes of ecological research include: (1) how organisms adapt to their environment, (2) how the numbers and distribution patterns of organisms in an area are influenced by environmental factors, and (3) changes in the number of organisms in an area over time and how the environment influenced these changes.

One of the major areas of interest in ecology is the flow of energy through an ecosystem. The source of almost all life on Earth is energy from the Sun, in the form of sunlight. That energy is captured by green plants in the process known as photosynthesis. When herbivorous (plant-eating) animals consume plants, they incorporate solar energy stored in those plants into their own bodies. Later, carnivorous (meat-eating) animals consume the herbivores, and solar energy is passed another step through the living world. Eventually, plants and animals die and are consumed by organisms known as decomposers (or detritivores). The complex of ecological relationships among all of the plants, animals, and decomposers is known as a food web.

The ultimate goal of ecology is to understand the nature of environmental influences on individual organisms, their populations and communities, on landscapes and, ultimately, the biosphere. If ecologists can achieve an understanding of these relationships, they will be able to contribute to the development of systems by which humans will be able to wisely use ecological resources, such as forests, agricultural soils, and hunted animals such as deer and fish. This goal is a very important one because humans are, after all, completely reliant on ecological goods and services as their only source of life support.

Source : http://getmyarticles.com


Jumat, 17 April 2009

Geological classification of Serpentine & Alabaster

Marble = CaCO3

It is a kind of limestone that was transformed by heat and pressure (of overlaying rocks)

Serpentine = Mg3[(OH)4/Si2O3]
It belongs to the group of silicates

Soapstone = Mg3[(OH)2/Si4O10]
It belongs - as serpentine - to the silicate group. It is the same as talcum.

Serpentine is the result of long time alteration of igneous rocks under pressure (tectonic activity) and temperature. It's very difficult to distinguish minerals in this rocks, but they have a fybrous texture.

An eclogite is an entirely metamorphic rock, formed under very high levels of pressure & and temperature in special geologic places (the Alps, for example). They look like granite but, you know, they are green (because of the pyroxene) and have garnet (a red equi-dimensional mineral). Even if it is weathered you can distinguish its texture.

About jade, it is a mineral more than a rock. But a rock rich in jade looks like a green glassy mass. Sometimes its associated with eclogites.

Serpentine is a hydrated Magnesium Silicate, similar in chemical composition to asbestos (but not quite as dangerous). Rare, but can be found in areas of hydrothermal activity (minerals in solution forced through the rock by subterranean heating, e.g. igneous intrusions), and usually is found as veins in the rock.

Serpentine can occur in many colours, but the most prized is green. Its delicate colour variations have made it popular over the years. It is easily worked with hand tools. Like the Blue John in Derbyshire, Serpentine is also capable of being worked on a lathe. Some people like to fashion bowls or vases to show off the translucence of the mineral. It is soft (h4), easily carved, but often flawed, and has a greasy texture that takes a polish well.

Good Cornish Serpentine is difficult get hold of. There are some exposures on public places, but these are well worked. Most seams are privately owned.

Alabaster is normally Gypsum - a hydrated Calcium Sulphate, (but in the past a certain kind of limestone was also referred to as Alabaster).

Gypsum is a very soft mineral (h2) - you can scratch it with your fingernail, dissolves in water, affected by temperature, therefore best for indoor sculpture.

Formed in sedimentary rocks. The mineral is often disseminated in a mudstone, but can migrate into cavities forming nodules, bands and crystals. Sometimes very large seams are found.

Much more translucent, or even transparent, than Serpentine. Colour - usually white, but varies with impurities (often iron) - yellow, red, brown. Often associated with the weathering of sulphide ores, or salt deposits. Widespread geographically and in time. In UK it is common in Permian-Triassic, Jurassic and Cretaceous periods. However, finding really big pieces for large scale carving is not so easy.

Serpentine and Alabaster had their hey-day in C19th.

How Alabaster is formed and what causes different shades of colouration from red through yellow to green? Plus - what period of geological time was Alabaster formed in? Was it during the Jurassic period?

Serpentines are so nasty rocks. They are the result of alteration under pressure and temperature of originally basalts or gabros, ussually with the presence of water. So they turn into greenish masses with fybrous texture. Their chemical composition is similar to
basalts or gabros: 45 -50% of SiO2, low content of K and Na, high content of Fe, Mg, and Mn; all these form far, of course.

About alabaster, it is just a variety of gypsum. All these rocks are formed by deposition of CaSO4 solved in salty water from lakes or sea, that evaporate. Layers of gypsum can be so old, even older than Jurassic (as you said), or be so young that formed just yesterday.

The alabaster that sculptors use comes from big and old layers... maybe Jurassic layers from Canada or USA.

The differences in colouration are the result of deposition conditions. Different colors mean different elements (as F, Cu, Zn, Cr, Ti, Mg) present inside the alabaster.


By yangxp

Structural Design Of Buildings And Safety From Seismic Upheavals

Nature and Probability

Although seismic upheavals earthquakes cannot be prevented in practice, science and engineering provide tools that can be used to reduce their effects quite substantially. Firstly, science can now identify where and when earthquakes are likely to occur, at what magnitude and determine the relative likelihood of a range of ground shaking levels. This information is readily available to architects, engineers, code writers, planners and to the general public. Secondly, seismic researchers and structural engineers with experience in seismic design have sufficient understanding of the effects of earthquake shaking on buildings to create designs that will be safe for various intensities of shaking. Modern building codes incorporate all of this information and require buildings to have structural engineering designs appropriate for each region.

However, earthquakes are complex phenomena and the exact nature of ground shaking and a building’s response to that shaking, are still covered in considerable uncertainty.

Earthquakes: A Worldwide Problem

Most people now know that although most frequent in California and Alaska, earthquakes are not restricted to just a few areas in the United States. In fact, two of the greatest earthquakes in U.S. history occurred not in California. 37 of 50 USA States have regions with sufficient seismic risk and hence require structural engineering designs more stringent than the normal seismic zones. The likelihood of a damaging earthquake occurring west of the Rocky Mountains—and particularly in California, Alaska, Oregon and Utah—is much greater than it is in the East or South. However, the New Madrid and Charleston regions are subject to potentially more severe earthquakes, although with a lower probability, than most regions of the western United States. According to the IBC (International Building Code) structural design maps and the USGS (US Geological Survey) hazard maps upon which they are based, other locations should also plan for intermediate ground motions.

Seismic Structural Engineering Design

Seismic design is highly developed, complex and strictly regulated by international codes and standards. Seismic codes present criteria for the design and construction of new structures subject to earthquake ground motions in order to minimize the hazard to life and to improve the capability of essential facilities to function after an earthquake. To these ends, current building codes provide the minimum requirements necessary for reasonable and prudent life safety.

Performance-based Seismic Structural Engineering Design Requirements:

- An engineering system for establishing the ground motion at given site based on seismic index and soil type
- Thorough seismic analysis of the existing building structure and systems
- Meticulous design requirements for building materials, systems and structure components
- Full description of irregular and asymmetrical building configurations and limitations on their use
- Building height limitations related to structural type and level of seismicity

For further information and explanation on structural engineering designs of residential and commercial buildings kindly email us at info@outsourcestructuraldrafting.com


By Richard Botham Botham

How to Design a Permanent Geological Exposure in a Landfill

One of the most common locations for landfills are worked out quarries and quarries suitable for landfill are an increasingly valuable resource for this reason.

In a growing number of cases suitable sites include rare geological exposures of mineral bearing rock, or strata of regional importance which need to be kept exposed after landfilling for educational and also often for historical reasons.

These SSI's can result in conflict between conservation and waste disposal interests.

Where quarries used for waste disposal contain Sites of Special Scientific Interest, it is necessary to maintain safe long term access to the geological exposure.

However, it is possible to minimise the conflict and to provide for these geological SSI's without undue difficulty, as we will describe.

The following list of considerations is broadly based on research described funded by the Nature Conservancy Council in the early 1990s, and has led to the identification of engineering measures designed to optimise landfill void in quarries whilst protecting, in the long term, geological Sites of Special Scientific Interest.

To provide long term, safe, unhindered access to the geological exposure with minimal sterilisation of landfill void space for waste, it is necessary to provide an engineered structure which limits land-take and which maintains a safe and secure perimeter barrier to the waste material.

The presence of a geological exposure in a quarry used as a landfill may have a significant effect on the design and operation of the landfill particularly with respect to leachate management.

Natural drainage should be provided where possible to prevent the accumulation of surface water adjacent to the geological exposure. Where this is not possible or the base of the geological exposure is below the water table, pumping may be necessary to facilitate access to the exposure.

It may be necessary to take measures to prevent the movement of leachate from the landfill site through or beneath the waste retaining structure towards the Site of Special Scientific Interest where it may contaminate accumulating surface and groundwater.

Landfill gas is flammable, is explosive if ignited in an enclosed space, and can also create an asphyxiating atmosphere. In Europe gas hazard sites (such as landfills) are controlled by the ATEX Directive and national regulations, such as the UK's Dangerous Substances and Explosive Atmospheres Regulations.

Where the landfill perimeter slopes adjacent to the geological exposure are engineered and graded to a profile of less than 1:3 access by visitors on foot across mown ground should present no significant problems if all visitors wear suitable footwear.

However, if the above criteria are met, there is no reason why a geological SSI and a landfill cannot co-exist without a significant conflict of interest.


By Steve Evans

How to Design a Permanent Geological Exposure in a Landfill

One of the most common locations for landfills are worked out quarries and quarries suitable for landfill are an increasingly valuable resource for this reason.

In a growing number of cases suitable sites include rare geological exposures of mineral bearing rock, or strata of regional importance which need to be kept exposed after landfilling for educational and also often for historical reasons.

These SSI's can result in conflict between conservation and waste disposal interests.

Where quarries used for waste disposal contain Sites of Special Scientific Interest, it is necessary to maintain safe long term access to the geological exposure.

However, it is possible to minimise the conflict and to provide for these geological SSI's without undue difficulty, as we will describe.

The following list of considerations is broadly based on research described funded by the Nature Conservancy Council in the early 1990s, and has led to the identification of engineering measures designed to optimise landfill void in quarries whilst protecting, in the long term, geological Sites of Special Scientific Interest.

To provide long term, safe, unhindered access to the geological exposure with minimal sterilisation of landfill void space for waste, it is necessary to provide an engineered structure which limits land-take and which maintains a safe and secure perimeter barrier to the waste material.

The presence of a geological exposure in a quarry used as a landfill may have a significant effect on the design and operation of the landfill particularly with respect to leachate management.

Natural drainage should be provided where possible to prevent the accumulation of surface water adjacent to the geological exposure. Where this is not possible or the base of the geological exposure is below the water table, pumping may be necessary to facilitate access to the exposure.

It may be necessary to take measures to prevent the movement of leachate from the landfill site through or beneath the waste retaining structure towards the Site of Special Scientific Interest where it may contaminate accumulating surface and groundwater.

Landfill gas is flammable, is explosive if ignited in an enclosed space, and can also create an asphyxiating atmosphere. In Europe gas hazard sites (such as landfills) are controlled by the ATEX Directive and national regulations, such as the UK's Dangerous Substances and Explosive Atmospheres Regulations.

Where the landfill perimeter slopes adjacent to the geological exposure are engineered and graded to a profile of less than 1:3 access by visitors on foot across mown ground should present no significant problems if all visitors wear suitable footwear.

However, if the above criteria are met, there is no reason why a geological SSI and a landfill cannot co-exist without a significant conflict of interest.


By Steve Evans

3d Models for Use in Geological Modeling

Geological modeling serves the purpose of creating 3D models of sections of the earths crust. These 3D models are unique as they can be created with different types of simulations of rocks, even the types of cells within the rocks. 3D models allow seismologists to predict certain events within the crust of the earth from shifting plates to eroding areas of the crust, or new growth within certain areas.

The grid surfaces within the programs are created with diverse polygons representing different structures and types of surfaces. These geological models are created using polygonal modeling using a meshed shell to create a surface that has been triangulated for the specific area.

3D geological modeling incorporates many other aspects of the field, including; diagenesis, structural geology, paleoclimatology and sedimentology.

Oil and Gas industries use these models to determine how the ground will react when the drills are inserted. These models are used to plan for any disturbances that may occur, as well as any weak points within the crust that could cause difficulty. If an accident were to occur, the 3D model allows the engineers to determine a plan of action for a variety of outcomes that may occur.

3D geological models are also used to complete valuable calculations for use in geostatistics. Many times, geologists are unable to calculate what is within the rock or within the crust at certain areas and therefore it is important to have software that can calculate these variables. This data is not available on regular grids and therefore must be estimated in the most effective manner.

Many popular software systems have been developed to create these 3D geologic 3D models; Roxar, Paradigm and Jewel suite are only a sample of the programs available. These powerful software systems are able to display and calculate parameters required for many professionals involved in Earth Sciences.


Source : www.articlesbse.com

Concept of Stratigraphy in Geology and Archaeology

Concept of Stratigraphy in Geology and Archaeology

Stratigraphy is based on superimposition. This is a simple concept stating that as layers of soil accumulate, the older deposits become progressively more deeply buried. Therefore each layer in a sequence of soil is younger than the one below it. In reality the situation usually is much more complex than this.

In archaeology we see that cuts (such as pits, ditches, post-holes and cellars) disturb this simple sequence. However, superimposition still works. The pit, etc is younger than (and therefore stratigraphically above) the layers through which it has been cut. Its fill will be younger than the pit cut itself. A layer that covers both the pit fill and the surrounding soil will be younger than both of them. The situation becomes even more complex when a later pit is cut through the first pit fill. Careful excavation is needed to sort out such complex stratigraphy.

In geology, the same concept is valid, as erosion (such as channels, rivers, valleys) disturb a superimposed sequence. The erosion is younger than the layer below it. The fill of this erosion is even younger than the erosion itself. If the erosion and the fill is covered with new layers, these are the youngest in the sequence.

Back to our archaeology example and tell you about other scenarios.
Sometimes we find ourselves digging something that appears to belong to an earlier period than the layer below it. For instance, after a ditch has been dug, material from outside (i.e. stratigraphically earlier) may collapse into it as a large block. It now appears that the ditch contains soil that is actually older than the ditch itself. In reality however, the soil has been moved ('re-deposited') from its original position and this makes it stratigraphically a new deposit. Again careful excavation is needed to identify such re-deposited layers and avoid obtaining erroneous dates from them.

In geology this example could be erosion of older rocks from somewhere else and transported into a new area with f.inst rivers or even an avalanche. These rocks are deposited on existing rocks in their new place, and are therefore superimposed on rocks deposited before, however the transported rocks can be older than the ones they are superimposed on. We say these older rocks are deposited later, however are older than the rocks they are deposited upon.

Disentangling these relationships is part of the challenge and fun of geology and archaeology. Within geology these studies form basic principle for exploration for oil and gas traps, and is referred to as sequence stratigraphy.

Source : www.articlesbase.com

A Career in Geology

These days this field of Geology is growing in popularity, and there are many jobs available. However, before choosing this field as a career choice, it is important to find out what it entails.

What Does Being A Geologist Entail?

A geologist is someone who studies the earth's composition, mainly the different kinds of rock formations. It also involves the study of organisms that inhabit it. The science deals with the analysis of the Earth and its origin, history, and minerals. Some of the branches of Geology are Mineralogy, Geological Engineering and Geomorphology, to name a few.

Geologists play an extremely important role in exploring and discovering natural resources and the mineral wealth of the earth. The main functions of a geologist entail observing natural calamities and their various effects on the environment, and to explore mineral, oil and natural gas fields and underwater resources. Their observations of the structure of the earth and the soil is important to evaluate if the conditions in certain areas are suitable for constructing bridges, roads and buildings, and for laying railway tracks.

Furthermore, some geologists also search for deep-sea natural resources. Oil exploration is another field that requires the services of geologists. Geologists can determine the quality of soil by conducting geo-chemical and geo-physical tests. Based on reports made by them, construction of roads, reservoirs underground tunnels and bridges can be undertaken. Overall, becoming a geologist involves a lot of knowledge and expertise.

Careers in Geology

Geology, as a career choice today, is more exciting than it ever was. Whether out on the field as backpackers, or indoors in the lab, it involves adventure and deep exploration of our planet. The field is wide ranging and offers a plethora of job opportunities. Nevertheless, it is advisable to first find out what kinds of geologist careers are available before you go ahead and make your decision.

People studying geology have the option of becoming geographers, geologists, oceanographers or meteorologists. Since geologists play an important role in finding valuable mineral resources, the avenues for them in the private and public sectors are vast. Careers in geology range from studying and predicting natural and man-made disasters to exploring mineral resources. Here are some additional careers that you can pursue if you have a degree in geology:

-Petrology
-Paleontology
-Volcanolo
-Geochemistry
-Geophysics
-Mining
-Environmental Education
-Environmental Law
-Environmental Consultant
-Research and Field Study

If you are planning on pursuing one of these careers, then information can be obtained through the Internet. Additionally, there are various books and resources that are dedicated to imparting knowledge and information on the subject of geology.

On the whole, pursuing a career in geology is an awe-inspiring and satisfying experience. Not only is this field fascinating, these days it also pays very well. If you are interested in the environment, the processes and the structure of the earth, its evolution, and the organisms that live within it, geology as a field would be an ideal choice for you.

Source : www.articlesbase.com