Category Geology

A rural area is an open swath of land that has few homes or other buildings, and not very many people. 

A rural areas population density is very low. Many people live in a city, or urban area. Their homes and businesses are located very close to one another. In a rural area, there are fewer people, and their homes and businesses are located far away from one another.

Agriculture is the primary industry in most rural areas. Most people live or work on farms or ranches. Hamlets, villages, towns, and other small settlements are in or surrounded by rural areas. 

Wildlife is more frequently found in rural areas than in cities because of the absence of people and buildings. In fact, rural areas are often called the country because residents can see and interact with the country’s native wildlife.

Throughout the world, more people live in rural areas than in urban areas. This has been changing rapidly, however. Urbanization is happening all over the world. In Asia, for example, the United Nations estimates that the urban population will increase by almost 2 billion by 2050. 

Open spaces:

These are common in rural areas. Some are conservation areas that are specially protected. The purpose of an open space reserve may include the preservation or conservation of a community or region’s rural natural or historic character; the conservation or preservation of a land or water area for the sake of recreational, ecological, environmental, aesthetic, or agricultural interests; or the management of a community or region’s growth in terms of development, industry, or natural resources extraction.

Facilities:

Rural areas often have few or no shops, hospitals, or post offices. Peoples may have to travel to the city to find them. People in rural areas generally have less access to healthcare than their urban counterparts. Fewer medical practitioners, mental health programs and healthcare facilities in these areas often mean less preventative care and longer response times in emergencies. The lack of healthcare workers has resulted in unconventional ways of delivering healthcare to rural dwellers, including medical consultations by phone or internet as well as mobile preventative care and treatment programs. There have been increased efforts to attract health professionals to isolated locations, such as increasing the number of medical students from rural areas and improving financial incentives for rural practices.

Settlements:

Settlement refers to the physical spaces and environments in which households are sheltered, and how one shelter relates to others. The term is generally used in the context of displaced populations to describe the temporary or sometimes permanent living arrangements of displaced families. In this context settlements can range from planned camps to dispersed accommodation in host villages/neighbourhoods, collective centres, and spontaneous camps, etc.

A rural settlement is where displaced populations settle on land outside of cities and towns. The population is often dependent on agricultural and pastoral practices, and has fewer community infrastructure systems than in urban settlements.

Agricultural:

A lot of the land in rural areas is used for growing crops and rearing animals for food. In rural areas throughout the world, agriculture represents the predominant land use and a major component of the viability of rural areas. Farming and related activities make up the basic fabric of rural life, contributing significantly to the overall state of rural regions in terms of employment and business opportunities, infrastructure and quality of the environment.

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Rocket and minerals make up much of our planet. They are formed deep inside the Earth over millions of Years. Rocks exist in lots of different shape, textures, and colours. They are mined to provide any of the things around us. Can you guess which rock is used where?

Granite:

Granite is and igneous rock which has extremely good weathering properties because it is very hard. This hardness makes it relatively difficult to work. Granite has been used in a large number of important buildings in the UK including Truro Cathedral, London Tower Bridge, Parts of St Pauls Cathedral, and Nelson’s Column. Granite has been mostly mined in the South West of England (Devon and Cornwall and in Aberdeenshire. Aberdeen is called the Granite City.

Iron ore:

Earth’s most important iron ore deposits are found in sedimentary rocks. They formed from chemical reactions that combined iron and oxygen in marine and fresh waters. The two most important minerals in these deposits are iron oxides: hematite (Fe2O3) and magnetite (Fe3O4). These iron ores have been mined to produce almost every iron and steel object that we use today – from paper clips to automobiles to the steel beams in skyscrapers.

Turquoise:

Turquoise is an opaque mineral that occurs in beautiful hues of blue, bluish green, green, and yellowish green. It has been treasured as a gemstone for thousands of years. Isolated from one another, the ancient people of Africa, Asia, South America and North America independently made turquoise one of their preferred materials for producing gemstones, inlay, and small sculptures.

 Rock salt:

Rock Salt is a chemical sedimentary rock that forms from the evaporation of ocean or saline lake waters. It is also known by the mineral name “halite”. It is rarely found at Earth’s surface, except in areas of very arid climate. It is often mined for use in the chemical industry or for use as a winter highway treatment. Some halite is processed for use as a seasoning for food. 

Marble:

Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite (CaCO3) and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite. Under the conditions of metamorphism, the calcite in the limestone recrystallizes to form a rock that is a mass of interlocking calcite crystals. A related rock, dolomitic marble, is produced when dolostone is subjected to heat and pressure.

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There are three different groups of rock: igneous, sedimentary, and metamorphic. Rocks are classified into these three different groups, depending on how they were formed.

Igneous rock:

Igneous rocks (from the Greek word for fire) form from when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.

Intrusive Igneous Rocks:
Intrusive, or plutonic, igneous rock forms when magma is trapped deep inside the Earth. Great globs of molten rock rise toward the surface. Some of the magma may feed volcanoes on the Earth’s surface, but most remains trapped below, where it cools very slowly over many thousands or millions of years until it solidifies. Slow cooling means the individual mineral grains have a very long time to grow, so they grow to a relatively large size. Intrusive rocks have a coarse grained texture.

Extrusive Igneous Rocks:
Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth’s surface. These are the rocks that form at erupting volcanoes and oozing fissures. The magma, called lava when molten rock erupts on the surface, cools and solidifies almost instantly when it is exposed to the relatively cool temperature of the atmosphere. Quick cooling means that mineral crystals don’t have much time to grow, so these rocks have a very fine-grained or even glassy texture. Hot gas bubbles are often trapped in the quenched lava, forming a bubbly, vesicular texture.

Sedimentary rock:

Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in four main ways: by the deposition of the weathered remains of other rocks (known as ‘clastic’ sedimentary rocks); by the accumulation and the consolidation of sediments; by the deposition of the results of biogenic activity; and by precipitation from solution.

Sedimentary rocks include common types such as chalk, limestone, sandstone, clay and shale.

Sedimentary rocks cover 75% of the Earth’s surface.

Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion) caused mainly by friction of waves, transportation where the sediment is carried along by a current, deposition and compaction where the sediment is squashed together to form a rock of this kind.

Sedimentary rocks are formed from overburden pressure as particles of sediment are deposited out of air, ice, or water flows carrying the particles in suspension.

As sediment deposition builds up, the overburden (or ‘lithostatic’) pressure squeezes the sediment into layered solids in a process known as lithification (‘rock formation’) and the original connate fluids are expelled.

The term diagenesis is used to describe all the chemical, physical, and biological changes, including cementation, undergone by sediment after its initial deposition and during and after its lithification, exclusive of surface weathering.

Metamorphic rock:

Metamorphic rocks are rocks that have become changed by intense heat or pressure while forming. In the very hot and pressured conditions deep inside the Earth’s crust, both sedimentary and igneous rocks can be changed into metamorphic rock. In certain conditions these rocks cool and crystallize usually into bands of crystals. Later they can become exposed on Earth’s surface. One way to tell if a rock sample is metamorphic is to see if the crystals within it are arranged in bands.

One way to think about the metamorphic process (metamorphism) is to consider what happens when soft clay objects are put into a kiln and heated to a very high temperature. They change from being squashy to rock hard. They cannot be changed back to their original form. The material has been changed. This is what happens on a huge scale underground producing metamorphic rock.

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All of the land on Earth is divided up into seven large areas, called continents. These are North America, South America, Europe, Africa, Asia, Australia, and Antarctica. Each continent is divided u p again into a number of different countries.

North America:

This is the third largest continent, and has the fourth-largest population. North America runs from the America runs from the Arctic down to the equator, so the climate varies a lot.

North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, or simply the Americas. Mainland North America is shaped roughly like a triangle, with its base in the north and its apex in the south; associated with the continent is Greenland, the largest island in the world, and such offshore groups as the Arctic Archipelago, the West Indies, Haida Gwaii (formerly the Queen Charlotte Islands), and the Aleutian Islands.

South America:

South America, fourth largest of the world’s continents. It is the southern portion of the landmass generally referred to as the New World, the Western Hemisphere, or simply the Americas. The continent is compact and roughly triangular in shape, being broad in the north and tapering to a point—Cape Horn, Chile—in the south.

South America is bounded by the Caribbean Sea to the northwest and north, the Atlantic Ocean to the northeast, east, and southeast, and the Pacific Ocean to the west. In the northwest it is joined to North America by the Isthmus of Panama, a land bridge narrowing to about 50 miles (80 km) at one point. Drake Passage, south of Cape Horn, separates South America from Antarctica.

Antarctica:

Antarctica, fifth in size among the world’s continents. Its landmass is almost wholly covered by a vast ice sheet.

Lying almost concentrically around the South Pole, Antarctica—the name of which means “opposite to the Arctic”—is the southernmost continent, a circumstance that has had momentous consequences for all aspects of its character. It covers about 5.5 million square miles (14.2 million square km), and would be essentially circular except for the outflaring Antarctic Peninsula, which reaches toward the southern tip of South America (some 600 miles [970 km] away), and for two principal embayments, the Ross Sea and the Weddell Sea. These deep embayments of the southernmost Pacific and Atlantic oceans make the continent somewhat pear-shaped, dividing it into two unequal-sized parts. The larger is generally known as East Antarctica because most of it lies in east longitudes. The smaller, wholly in west longitudes, is generally called West Antarctica. East and West Antarctica are separated by the approximately 2,000-mile- (3,200-km-) long Transantarctic Mountains. Whereas East Antarctica consists largely of a high ice-covered plateau, West Antarctica consists of an archipelago of mountainous islands covered and bonded together by ice.

Europe:

Europe, second smallest of the world’s continents, composed of the westward-projecting peninsulas of Eurasia (the great landmass that it shares with Asia) and occupying nearly one-fifteenth of the world’s total land area. It is bordered on the north by the Arctic Ocean, on the west by the Atlantic Ocean, and on the south (west to east) by the Mediterranean Sea, the Black Sea, the Kuma-Manych Depression, and the Caspian Sea. The continent’s eastern boundary (north to south) runs along the Ural Mountains and then roughly southwest along the Emba (Zhem) River, terminating at the northern Caspian coast.

Europe’s largest islands and archipelagoes include Novaya Zemlya, Franz Josef Land, Svalbard, Iceland, the Faroe Islands, the British Isles, the Balearic Islands, Corsica, Sardinia, Sicily, Malta, Crete, and Cyprus. Its major peninsulas include Jutland and the Scandinavian, Iberian, Italian, and Balkan peninsulas. Indented by numerous bays, fjords, and seas, continental Europe’s highly irregular coastline is about 24,000 miles (38,000 km) long.

Africa:

Africa, the second largest continent (after Asia), covering about one-fifth of the total land surface of Earth. The continent is bounded on the west by the Atlantic Ocean, on the north by the Mediterranean Sea, on the east by the Red Sea and the Indian Ocean, and on the south by the mingling waters of the Atlantic and Indian oceans.

Africa’s total land area is approximately 11,724,000 square miles (30,365,000 square km), and the continent measures about 5,000 miles (8,000 km) from north to south and about 4,600 miles (7,400 km) from east to west. Its northern extremity is Al-Gh?r?n Point, near Al-Abya? Point (Cape Blanc), Tunisia; its southern extremity is Cape Agulhas, South Africa; its farthest point east is Xaafuun (Hafun) Point, near Cape Gwardafuy (Guardafui), Somalia; and its western extremity is Almadi Point (Pointe des Almadies), on Cape Verde (Cap Vert), Senegal. In the northeast, Africa was joined to Asia by the Sinai Peninsula until the construction of the Suez Canal. Paradoxically, the coastline of Africa—18,950 miles (30,500 km) in length—is shorter than that of Europe, because there are few inlets and few large bays or gulfs.

Australia:

Australia is a continent in the Southern Hemisphere, which comprises the countries of Australia, Tasmania, Seram, New Guinea, Timor, and other neighbouring islands. It is the smallest among the seven continents of the world, and lies on a continental shelf. Shallow seas divide the continent in to the different landmasses. The Torres Strait and Arafura Sea separate the mainland of Australia and New Guinea, and the Bass Strait lies between Tasmania and mainland Australia. They were actually connected by dry land in earlier times during the time around 18,000 BC, when the sea levels were lower. It was the Pleistocene ice age then. The sea levels have risen in the past ten thousand years, and that overflowed the lands and separated the different landmasses. New Zealand is not a part of the continent of Australia, but of the separate continent of Zealandia which is submerged. Both New Zealand and Australia are parts of the wider regions well known by Oceania or Australasia.

Asia:

Asia, the world’s largest and most diverse continent. It occupies the eastern four-fifths of the giant Eurasian landmass. Asia is more a geographic term than a homogeneous continent, and the use of the term to describe such a vast area always carries the potential of obscuring the enormous diversity among the regions it encompasses. Asia has both the highest and the lowest points on the surface of Earth, has the longest coastline of any continent, is subject overall to the world’s widest climatic extremes, and, consequently, produces the most varied forms of vegetation and animal life on Earth. In addition, the peoples of Asia have established the broadest variety of human adaptation found on any of the continents.Africa: This is the second-largest continent and has the most countries. The world’s longest river and the world’s largest desert are in Africa.

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Rocks go through many changes over time. These are caused by different processes, such as heating, cooling, and weathering. The sequence of changes is called the rock cycle.

Igneous rock:

Igneous rocks form by the cooling of magma (molten rock material beneath the surface) or lava (molten rock material extruded onto the surface). Magma which originates at depths as great as 200 kilometers below the surface consists primarily of elements found in silicate minerals along with gases, notably water vapor. Because the molten material is less dense than the surrounding solidified rock, it works its way toward the surface where it flows out onto the surface as lava.

Cooling:

What would you do to turn a melted chocolate bar back into a solid? You’d cool it by putting it into the refrigerator until it hardens.

Similarly, liquid magma also turns into a solid — a rock — when it is cooled. Any rock that forms from the cooling of magma is an igneous rock. Magma that cools quickly forms one kind of igneous rock, and magma that cools slowly forms another kind. 

When magma rises from deep within the earth and explodes out of a volcano, it is called lava, and it cools quickly on the surface. Rock formed in this way is called extrusive igneous rock. It is extruded, or pushed, out of the earth’s interior and cools outside of or very near the earth’s surface. 

What if the magma doesn’t erupt out of a volcano, but instead gets pushed slowly upward toward the earth’s surface over hundreds, thousands, or even millions of years? This magma will also cool, but at a much slower rate than lava erupting from a volcano. The kind of rock formed in this way is called intrusive igneous rock. It intrudes, or pushes, into the earth’s interior and cools beneath the surface. 

Melting:

What happens to a chocolate bar when it gets very hot? It melts.

The same thing happens to a rock when it is heated enough. Of course, it takes a lot of heat to melt a rock. The high temperatures required are generally found only deep within the earth. The rock is pulled down by movements in the earth’s crust and gets hotter and hotter as it goes deeper. It takes temperatures between 600 and 1,300 degrees Celsius (1,100 and 2,400 degrees Fahrenheit) to melt a rock, turning it into a substance called magma (molten rock). 

Metamorphic rock:

Metamorphic rocks are formed by the alteration of pre-existing rocks from exposure to heat and pressure while remaining in a solid form. Metamorphism occurs by breaking bonds between atoms in a mineral so that the atoms rearrange themselves into new, more stable, mineral forms. Rocks are transformed and remain in a solid state because not all the bonds in the rock’s minerals are broken – if they were the rock would melt.  Metamorphism occurs in solid rock because only some of the bonds between atoms are broken in an unstable mineral. As a result, the freed atoms and ions can migrate to another location within the mineral, or bond with atoms in a different mineral. The end result is to produce minerals that are more stable under the environmental conditions in which they exist. 

Metamorphism involves the transformation of a pre-existing rock to form new minerals and textures. The original mineral content of a rock can change in several ways. Unstable minerals like clay will breakdown and their elements will recombine to form new minerals. More stable minerals like quartz, will stay quartz but change shape and size to form a new configuration. At high temperatures, atoms and ions may move into a new orientation and bond into more stable forms. Hence, the type of minerals and its texture may change but the chemical composition of the rock itself can stay the same.

Uplift:

Understanding the idea of Uplift is the key to making sense of the rock cycle, as it allows us to see rocks that were once deeply buried beneath the surface.

If rocks did not get uplifted to form hills and mountains, then the processes of weathering and erosion would long ago have reduced much of the world’s land-masses to low-lying, flat plains. Weathering and erosion, transport and deposition would all effectively stop.

Scientists believe that, if all these active processes of the rock cycle ceased to operate, then our planet would cease to be able to support any life.

Mount Everest is made of limestone that must have originally formed on an ancient sea floor because it contains fossils of marine creatures.

Heat and Pressure:

The atoms in rocks rearrange to form bigger and heavier minerals. The combination of heat and pressure may cause the minerals in the rock to split into layers. Metamorphic rocks begin changing at temperatures of 100 degrees Celsius to 800 degrees Celsius. If you squeeze and heat a rock for a few million years, it can turn into a new kind of rock. 
The pressure comes from many layers of rock piling on top of each other, and the heat comes from magma.  It’s like putting blankets on yourself – the more you layers you put on, or the more blankets you put on, the more pressure you receive because of all the weight of the layers on top of you.

Sedimentary rock:

Sedimentary rocks are those formed from the compaction and cementation of fragments of pre-existing rocks called clasts, or plant and animals remains. The exogenic processes of weathering and erosion create the raw materials for sedimentary rocks. Earth material is loosened and moved from higher to lower elevations where it is deposited as transportation agents like water, wind or gravity lose their energy to move sediment. Streams and rivers transport sediment to lakes or oceans, or deposits it on nearby floodplains where it accumulates. On land, clastic sediments consist mainly of large boulders, cobbles, gravel, sand, and silt. On the continental shelves at the margin of continents, marine sediment is largely sand, silt, and clay. At the outer shelves and on the ocean floor, clays and chemically precipitated calcium carbonate and the remains of tiny marine animals accumulate.

Weathering and erosion:

Rocks are hard and strong, but they do not stay that way forever. Forces like wind and water break down rocks through the processes of weathering and erosion.

Weathering is the process that breaks down rocks. Many things cause weathering, including climate changes. Erosion breaks rocks down further and then moves them. Forces like wind and water move the rock pieces. They mix with matter like sand to become sediment. Weathering and erosion help shape Earth’s surface. They are part of a process called the rock cycle.

Transportation and deposition:

Eroded rock particles are carried away by wind or by rain, streams, rivers, and oceans. As rivers get deeper or flow into the ocean, their current slows down, and the rock particles (mixed with soil) sink and become a layer of sediment. Often the sediment builds up faster than it can be washed away, creating little islands and forcing the river to break up into many channels in a delta.

Sedimentation and cementation:

Cementation, in geology, hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of a sedimentary rock. The cement forms an integral and important part of the rock, and its precipitation affects the porosity and permeability of the rock. Many minerals may become cements; the most common is silica (generally quartz), but calcite and other carbonates also undergo the process, as well as iron oxides, barite, anhydrite, zeolites, and clay minerals.

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Soil is made up of broken rocks, minerals, decaying plants and animals, tiny creatures, gases, and water. If a section is cut through soil, you will see many layers. The depth of the layers vary in different soils.

Humus:

Humus, nonliving, finely divided organic matter in soil, derived from microbial decomposition of plant and animal substances. Humus, which ranges in colour from brown to black, consists of about 60 percent carbon, 6 percent nitrogen, and smaller amounts of phosphorus and sulfur. As humus decomposes, its components are changed into forms usable by plants.

Topsoil:

It is also called the humus layer, which is rich in organic material. This layer consists of decomposed material and organic matter. This is the reason; the topsoil has a dark brown color. The hummus makes the topsoil soft, porous to hold enough air and water. In this layer, the seeds germinate and roots of the plants grow. Many living organisms like earthworms, millipedes, and centipedes, bacteria, and fungi are found in this layer of soil.

Leaching layer:

Leaching, loss of soluble substances and colloids from the top layer of soil by percolating precipitation. The materials lost are carried downward (eluviated) and are generally redeposited (illuviated) in a lower layer. This transport results in a porous and open top layer and a dense, compact lower layer. The rate of leaching increases with the amount of rainfall, high temperatures, and the removal of protective vegetation. In areas of extensive leaching, many plant nutrients are lost, leaving quartz and hydroxides of iron, manganese, and aluminum. This remainder forms a distinctive type of soil, called laterite, or latosol, and may result in deposits of bauxite. In such areas rapid bacterial action results in the absence of humus in the soil, because fallen plant material is completely oxidized and the products are leached away. Accumulations of residual minerals and of those redeposited in lower layers may coalesce to form continuous, tough, impermeable layers called duricrusts.

Weathered rock:

Weathering is the name given to the process by which rocks are broken down to form soils. Rocks and geological sediments are the main parent materials of soils (the materials from which soils have formed). There is a very wide variety of rocks in the world, some acidic, some alkaline, some coarse-textured like sands, and some fine-textured and clayey. It is from the rocks and sediments that soils inherit their particular texture. When you see rocks in the landscape it is easy to appreciate how long the process of breaking down rocks to form soil takes. In fact, it can take over 500 years to form just one centimetre of soil from some of the harder rocks. Fortunately, in some respects at least, huge amounts of rocks were broken down during the Ice Age over 10,000 years ago and converted into clay, sands or gravels, from which state it was easier to form soils.

Subsoil:

It is comparatively harder and compact than topsoil. It is lighter in color than the topsoil because there is less humus in this layer. This layer is less organic but is rich in minerals brought down from the topsoil. It contains metal salts, especially iron oxide in a large proportion. 

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