Geography & EVS

Drainage Pattern : The land area whose runoff drains through a single stream is called that stream’s DRAINAGE BASIN. The area outside the Roney Building at GSW, for instance, provides runoff to the small stream that drains College Lake, and so is in the drainage basin of that stream. That stream feeds Willet Creek a few dozen meters downstream and so we are also in the Willet Creek drainage basin. Willet Creek is tributary to Mill Creek, Mill Creek to Muckalee Creek, Muckalee to the Flint River, and the Flint to the Appalachicola, which drains into the Gulf. The Roney building therefore sits in the drainage basin of each of these streams in turn.The high ground that separates two drainage basins is called a DRAINAGE DIVIDE. The Pelham Escarpment (a hill which one climbs south of Cordele on I-75) separates the drainage basins of the Apalachicola system from that of the Suwannee system, and so is the drainage divide between those basins.How water drains out of an area depends upon the bedrock geology of that area. There are numerous patterns that drainage systems follow; we will examine only four of them as summarized in the diagram below. The next page shows examples and discusses each in more detail. ENDRITIC drainage arises on rocks that are consistently resistant to erosion and/or flat-lying. As valleys develop they erode their way headward in random directions (always uphill, of course). Because “uphill” is, in general, away from the mouth of the stream, the pattern of tributary branching tends to resemble the upward branching of a tree. The name comes from the Greek rootdendros which means “tree”.The southernmost half or so of Georgia is called the Coastal Plain. This region is underlain by horizontally bedded, young, soft sediments and this is why dendritic drainage has formed here. Much of the rest of the state, excepting only the northernmost counties, is called the Piedmont. This is a stage 3 (“old”) erosional surface on metamorphic and igneous rocks that are, for the most part, consistently resistant to erosion. This is why dendritic drainage has formed here. Some parts of the Piedmont, the Blue Ridge (northeastern corner) and Valley and Ridge (northwestern corner) are not geologically like this and so may have different drainage types.A different type of drainage forms on sedimentary rocks that are tilted or folded and that have different susceptibilities to erosion. In such a situation the more resistant rocks tend to stand as high ridges whereas the more easily eroded softer rocks are cut down to form valleys. Both the ridges and the valleys are long parallel topographic features, running along the bands where the tilted beds intersect the Earth’s surface. Such topography is called “valley and ridge” topography. The province of that name in northwest Georgia has such a landscape.Where rocks are consistently hard but have been fractured by faulting or other processes a third type of drainage pattern forms. The fractures tend to occur in two sets that at some angle, sometimes 90°. The fractured rock is usually easier to erode that the pristine rock and so the streams in the region tend to follow along them, also meeting at consistent angles. In general this drainage type is called ANGULAR, but if the fractures and streams do meet at approximately right angles it can be calledRECTANGULAR DRAINAGE. The final drainage type occurs on circular mountains and round uplifted regions called “domes”. Most truly circular mountains are of volcanic origin, and so RADIAL DRAINAGE is usually associated with volcanoes. The map below shows the northern of a pair of small volcanic cones (the Menan Buttes) in southeastern Idaho. The closed depression at the top is, of course, the volcanic crater. even though there are no permanent streams that drain this mountain the “v’s” on the contour lines clearly show the locations of dry washes, and these drain away from the summit, as would be expected.

How Rocks Change Introduction Does it seem to you that rocks never change? For example, if you find a chunk of granite today, can you expect that it will still be granite at the end of your lifetime? That may well be true — but only because our lifetimes are very short relative to the history of the earth. If we take a step back to look at geologic time (which focuses on changes taking place over millions of years), we find that rocks actually do change! All rocks, in fact, change slowly from one type to another, again and again. The changes form a cycle, called “the rock cycle.” The way rocks change depends on various processes that are always taking place on and under the earth’s surface. Now let’s take a closer look at each of these processes. Heat & Pressure What happens to cookie dough when you put it in the oven? The heat of the oven produces changes in the ingredients that make them interact and combine. Without melting the dough, the heat changes it into a whole new product — a cookie. A similar process happens to rocks beneath the earth’s surface. Due to movements in the crust, rocks are frequently pulled under the surface of the earth, where temperatures increase dramatically the farther they descend. Between 100 and 200 kilometers (62 and 124 miles) below the earth’s surface, temperatures are hot enough to melt most rocks. However, before the melting point is reached, a rock can undergo fundamental changes while in a solid state — morphing from one type to another without melting. An additional factor that can transform rocks is the pressure caused by tons of other rocks pressing down on it from above; heat and pressure usually work together to alter the rocks under the earth’s surface. This kind of change, which results from both rising temperature and pressure, is called metamorphism, and the resulting rock is a metamorphic rock. Rock cycle :A useful way to illustrate how the three main types of rock are related to one another and how changes to rocks happen in a recurring sequence is the rock cycle. The concept of the rock cycle is attributed to James Hutton (1726–1797), the 18th-century founder of modern geology. The main idea is that rocks are continually changing from one type to another and back again, as forces inside the earth bring them closer to the surface (where they are weathered, eroded, and compacted) and forces on the earth sink them back down (where they are heated, pressed, and melted). So the elements that make up rocks are never created or destroyed — instead, they are constantly being recycled. The rock cycle helps us to see that the earth is like a giant rock recycling machine!

Types Of Rocks: The three main types, or classes, of rock are sedimentary, metamorphic, andigneous and the differences among them have to do with how they are formed. Sedimentary Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock. Generally, sedimentary rock is fairly soft and may break apart or crumble easily. You can often see sand, pebbles, or stones in the rock, and it is usually the only type that contains fossils. Examples of this rock type include conglomerate and limestone. Metamorphic Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface. Examples of this rock type include gneiss and marble. Igneous Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava). When lava cools very quickly, no crystals form and the rock looks shiny and glasslike. Sometimes gas bubbles are trapped in the rock during the cooling process, leaving tiny holes and spaces in the rock. Examples of this rock type include basalt and obsidian.  

Lakes: A lake is an area, (prototypically filled with water, also of variable size), localized in a basin, that is surrounded by land apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, and are also larger and deeper thanponds.[1][2] Lakes can be contrasted with rivers orstreams, which are usually flowing. However most lakes are fed and drained by rivers and streams.Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them Important Lakes in India There are amazingly beautiful and pleasant lakes in India. Some of these lakes are major tourist destination. Some important lakes have been discussed below: Jag Mandir Lake, Udaipur Lake Garden Palace or Jag Mandir is situated in Lake Pichola in Udaipur city of Rajasthan. The Palace was constructed by three Maharanas of Mewar Kingdom.The construction works were started during the reign of Maharana Amar Singh. This beautiful Palace is used to hold parties and as summer resort by the Royal family. Chilka Lake, Odisha The Chilka Lake is the major coastal lagoon of India and second largest in World, spread over three districts of Puri, Ganjam and Khurdah in Odisha with covered area of 1100 square kilometers. There more than 160 species of birds visit this lake in the peak season. The Lake is the home of 14 raptor types, 37 types of amphibians and reptiles, many types of fish. Dal Lake, Srinagar The Dal Lake or Srinagar’s Jewel is a beautiful urban lake is situated in Srinagar in Jammu & Kashmir. The Dal Lake is one of important place of interest by tourists and this lake is also used water plant harvesting and fishing. The Dal Lake is covered with the 18 square kilometer area and gets frozen in the winter season. Durgam Cheruvu, Hyderabad The Secret lake or Durgam Cheruvu is situated near Hyderabad, Andhra Pradesh. It is hidden between two localities of Madhapur and Jublee Hills, that’s why it is called secret lake. The Secret Lake is a fresh water lake and covered with 83 acres of area. Chandubi Lake, Assam Chandubi Lake is situated at the bottom of Garo Hills in Kamrup district of Assam. The nearest city is Guwahati which is 64 km away from it. This lake surrounded by calm and deep forest which attracts many migratory birds in the winter season. Thol Lake, Ahmedabad Thol Bird Sanctuary or The Thol Lake is located in the district of Mehsana in Gujrat. This fresh water lake is a home of 100 species of birds. The nearest city is Ahmedabad which is 40 km away from it. Renuka Lake, Himachal Pradesh The largest Lake of Himachal Pradesh is the Renuka Lake which is a low altitude lake with height of 672 meter above sea level. The main season to visit is November as annual fair is held every year. There are attractions like Lion Safari, Boating for tourists. The Renuka Sanctuary is situated beside the Renuka Lake. Manasbal Lake, Kashmir Valley Manasbal Lake is located in the district of Ganderbal in Jammu Kashmir. This lake is the deepest lake in India with 13 meter depth. The Mughal garden was built by Nur Jahan for beautify the lake. This lake is around 30 km away from Srinagar. Tsomoriri, Ladakh Tsomoriri Lake is situated in Changthang in Jammu & Kashmir at height of 4595 meter from sea level. This lake is the largest among high altitude lakes in the Trans Himalayan region.

Plains : Broad and flat, plains are well named. Some appear when glaciers and streams erode away elevated terrain; others spread where rising magma pushes, erupts, and spews. Some plains spill into the oceans, and others are bound by mountains on several sides. They all hide a tumultuous geologic history beneath their level disguise.The base of the vast Great Plains in North America formed when several small pieces of continental crust collided and welded together more than a billion years ago. As time marched forward, the base was filled with marine sediments as periodic shallow seas covered the region and glaciers, rivers, and streams eroded the Rocky and Appalachian Mountains. Today, mountain erosion continues to carry debris out onto the plains.When melting snows and heavy rains fill rivers beyond their banks, they flood. The waters spread out over the surrounding landscape and drop the load of mud, sand, and silt they normally channel downstream. Over thousands of years, the sediments build up floodplains.Alluvial plains often form where steep mountain valley rivers gush onto more level lands, forcing the rush of heavy waters to spill over their banks and drape their sediments out like a fan.Out on the wide-open valley floors, rivers twist and turn on a constant search for passage to the sea. The meandering path continues to widen the valley floor as falling sediment forever alters the course and builds up a river plain.The Snake River Plain stretches from Oregon across northern Nevada and southern Idaho into Wyoming. Its geologic history is a complicated tale of normal fractures in the Earth’s crust on its western edge to a more complex plot of basalt lava flows perhaps stemming from a hot plume of magma now beneath Yellowstone National Park.Coastal plains are stretches of lowland next to oceans that are separated from the interior by highland features such as mountains and plateaus. Often the plains are portions of the ocean floor built up from the sediments rivers carry towards the sea. Geologists call the submerged part of coastal plains thecontinental shelves.  

How Are Plateaus Formed ? Most of the plateaus of the earth are formed due natural geological uplift of the stable land areas of the earth’s crust which has been a gradual process. While some of the plateaus found between the mountains are formed as a result of collision of sections of the earth’s crust.Many of the plateaus are also formed due lava flowing from the large volcanoes that spread through large areas of land surface, building them up.The Famous Plateaus Of The WorldAs said that almost 45% of the earth’s surface consists of plateaus. There is a large community of living species on this earth living on plateaus. Many cities and even countries are formed on the plateaus.Kaiparowits Plateau, UtahFollowing are five famous plateaus of the world:The Colorado Plateau In US This plateau is found sprawled across the southeastern Utah, northern Arizona, northwestern New Mexico, and western Colorado. This roughly circular plateau covers approximately 130000 square miles of the land. The states of Texas, California, Alaska and Montana cover up the land of the plateau.It is believed that the Colorado plateau was originally a piece of land close to the sea level and was lifted up as a single mass of land nearly five million years ago.The elevation range of the Colorado plateau is from 3000-14000 feet average being 5200 feet which makes approximately 1585 metersDue to the high elevation of this plateau, the climatic conditions here are dry and arid. Because of its high precipitation of land and dry environment the plant accommodation on this plateau is less.The land of this plateau is eroded at places by winds and water forming dramatic landforms. The rivers have been cut into canyons within the plateau.

Types of mountains:Mountains can be classified into five different basic types based on the cause that formed the mountain, type of rocks, shape and placement on land.1. Fold Mountains (Folded Mountains)2. Fault-block Mountains (BlockMountains)3. Dome Mountains4. Volcanic Mountains5. Plateau Mountains Fold Mountains: These are the most common types of mountains. These are formed when two continental tectonic plates collide and their edges crumble to form mountains. The crust is uplifted forming folds on top of the other. Vast mountain ranges stretching across thousands of kilometres areFold Mountains. The Rocky Mountains in North America, the Alps in Europe, the Andes in South America, the Urals in Russia and the Himalayan Mountains in Asia are examples of Fold Mountains. Fault-Block Mountains: The Fault-block Mountains or block mountains are created when faults or cracks in the Earth’s crust force materials or blocks of rocks upward or down. The uplifted blocks are Block Mountains or horsts. The intervening dropped blocks are called graben, which can be small or form rift valley systems. These block mountains break up into chunks or blocks and move either up or down. When they move apart blocks of rock get stacked on one another Fault-block Mountains usually have a steep front side and then a sloping back side. The Sierra Nevada Mountains in North America and the Harz Mountains in Germany are examples of Fault-Block Mountains. Dome Mountains: Dome Mountains are also called Upwarped Mountains. These mountains are formed when large amounts of molten rock or magma push the earth’s crust from underneath. The magma in this case never reaches the top surface of the earth. So even before it can erupt the source of magma goes away leaving the pushed up Rock as such. This rock then cools and forms a mountain. With time the mountain forms a dome shape, where it gets warped due to erosion. The Black hills of South Dakota in the USA and the Adirondack Mountains in New York are examples for Dome Mountains. Volcanic mountains: Volcanic mountains are created by volcanoes as the name suggests. They are created when magma pushes its way from beneath the earth to the crust, and when it reaches the surface, it erupts as lava, ash, rocks and volcanic gases. These erupting materials build around the vent through which they erupted. These mountains are then shaped by further eruptions, lava flows, and collapses. Mount Fuji in Japan, MountRainer in the US, including Mauna Loa and Mauna Kea on the Big Island of Hawaii are examples of volcanic mountains. Plateau Mountains: Plateau Mountains are formed by Erosion. These are large areas of high levels of flat land, over 600 meters above sea level formed due to earth’s internal activity. Over billions of years, the rivers can cut deep into a plateau and make tall mountains. These mountains are found near Fold Mountains. The mountains in New Zealand and the Catskills of New York are examples of Plateau Mountains.the highest mountain on Earth is Mount Everest in the Himalayas. Mauna Loa, stands taller than Mount Everest when measured from its base on the ocean floor but not in terms of summit altitude. The tallest mountain in the solar system is Olympus Mons, located on Mars.Mountains and mountain ranges throughout the world have been left in their natural state, and are primarily used for recreation, while others are used for logging, mining, grazing. Hiking, backpacking, mountaineering, rock climbing, ice climbing, downhill skiing, and snowboarding are recreational activities enjoyed on mountains.Plateaus are in general referred to as the flat top mountains but by definition a plateau is defined as a large flat piece of land raised approximately more than 15000 feet above its surroundings, having at least one steep side.A plateau may occupy only a few square meters of the land or they maybe as large as thirty states of the United States.Plateaus are widespread through out the world and 45% of the earth’s surface consists of plateaus.

Mountains can be explained as landforms that rise well above the surrounding land for a limited area in the form of a peak. Mountains are steeper, larger and taller than hills and are more than 600 metres in height. Mountainous regions are called montane. The Oxford English Dictionary defines a mountain as a natural elevation of the earth surface rising more or less abruptly from the surrounding level and attaining an altitude which, relatively to the adjacent elevation, is impressive or notable. Many mountains are so high that they reach the colder layers of the atmosphere. This fact leads to different climates forests, flora and fauna in the same mountain. Mountain life is less preferable due to harsh climates, less suitability for agriculture and also less oxygen as we go higher up. Continental-continental convergenceHow are these mountains formed?The earth’s crust is made up of large plates called tectonic plates that fit into each other. These plates keep moving a few centimetres every year. Mountains form along the boundaries where the tectonic plates move towards each other (convergent boundaries). The tectonic plates collide triggering deformation and thickening of the crust. This in turn leads to crustal uplift and mountain formation. This process is a horizontal compression that leads to deformation folding and faulting of layers into folds or wrinkles along the convergent plate boundaries. This crustal uplift can be either a hill or a mountain depending upon the height and slope of the formation. But also to balance the weight of the earth surface, much of the compressed rock is forced downward, producing deep mountain roots making mountains for both upward and downward.Convergence due to converging plates can be either continental-oceanic convergence, oceanic-oceanic convergence or continental-continental convergence.1. When a plate of continental crust converges with a plate of oceanic crust, the heavier oceanic crust will move under the continental crust and this process is called subduction. This is the process through which mountains and volcanoes are formed when the subducted oceanic crust is melted and recycled to the surface (e.g. West coast of North and South America).2. When a place of oceanic crust converges with another plate of oceanic crust, the older crust will subduct under the newer crust that is less dense leading to volcanic ring islands (e.g. Japanese islands).3. When two plates of continental crusts come into contact with each other, neither of them will subduct beneath the other due to their densities. So this collision leads to formation of big mountains with fragments of oceanic sediments in them even in the highest peaks (e.g. Alps in Europe, Himalayas in Asia).

Differences and Similarities Between Plate Tectonics and Continental Drift :First, since there are many similarities between Plate Tectonics and Continental Drift, let’s brush up on the definitions of the two. Plate Tectonics is a theory of global tectonics in which the lithosphere is divided into a number of crustal plates, each of which moves on the asthenosphere. Continental Drift, however, is a theory developed by Alfred Wager who suggested that in the past, there was a super continent called Pangaea. Over time, this super continent split apart to form the seven continents we have today. One of the key difference between the newer plate tectonics and continental drift theories is that Wegener’s original theory of continental drift, and the more modern ideas called plate tectonics is that Wegener believed that each continent was propelled through the solid ocean floor. Some geologists thought this was completely absurd. The newer theory of plate tectonics states that the entire crust of the earth is broken into six large plates and many, many smaller ones. Any plate may consist of ocean floor and/or part of a continent or islands. The boundaries between plates are the mid-ocean ridges, where new oceanic crust is formed and plates move apart; ocean trenches and young mountains, where plates come together and older ocean crust is overridden and returned to the interior. A similarity between the two theories, however, is that both of the theories suggest the Earth is constantly moving. The theory of plate tectonics suggests that the plates that float on top of the asthenosphere, which hold continents, are always moving, and therefore have a tendency to bump into each other. Places where the plates meet each other are known as faults. There are usually some very large earthquakes near, or in faults. A very large fault, called the San Andreas fault, is located in California. The theory of Continental drift, suggests a very similar idea. However, this theory states that all the continents once fit together into a very large continent. There is plenty of evidence that supports this, too. You can find very similar fossils, and geology on both the east coasts of South America, and the west coast of Africa. Plus, they look like they could fit together, too. There is also similar evidence on both the east and west coasts of the U.S. and Europe. Although there are more similarities than differences, you have to remember that both theories suggest the exact same thing.

Continental Drift Theory:It is an interesting theory that was proposed in 1912 by a German meteorologist, Alfred Wegener. He theorized that the continents of the world— North and South America, Africa, Europe, Asia, Australia, and Antarctica—were once fused into a single super continent. He called it Pangaea (means “all earth”). According to this theory, Pangaea began to split apart around 200 million years ago until it reached its present state. And the continents continue to move. The Basis of Alfred Wegener’s Continental Drift TheoryHe based his theory on fossils discovered in Africa that matched those found in Brazil. He theorized that once upon a time, Africa and Brazil belonged to the same continent. Scientists during Wegener’s time were skeptical about his theory until the theory of tectonic plates was developed in 1960. The theory represented what is perhaps the greatest advance in the history of geology. Now geologists have a framework that explains the movement of continents, the occurrence of earthquakes, the existence of volcanoes, and the birth of mountains.The Theory of Tectonic PlatesAccording to the theory, moving plates make up the earth’s crust. They float on partly melted rock in the upper mantle. Since the continents are on top of these plates, they also move with the plates. The plates may crash head-on, pull-apart, or rub each other causing all sorts of geologic phenomena.When two plates collide head-on, mountains and mountain ranges are formed. When two plates collide, and one drives below the other, volcanoes emerge. If the lava breaks the surface, it piles up to form volcanic islands. The island of Japan was formed this way. If the islands move sidewise grinding their edges as they pass, friction builds up. This causes tremors and earthquakes. When plates under the ocean move away from each other, the earth’s crust may crack. Magma may ooze in this crack, creating volcanic islands (called sea mounts) under the sea. Finally, when a heavy oceanic plate hits a lighter continental plate, the lighter plate slides down (or become subducted) into the mantle. The plate’s edge melt and magma rises to the surface through volcanic mountains.When two continental plates ram into each other, compressing and uplifting the rock they carry, folded mountains are formed. Depending on the intensity of the collision and the types of rocks involved, the fold may range in height, from a few meters to several kilometers. The Himalayas in Asia, the Alps in Europe, and the Appalachian mountains in the United States are folded mountain ranges.When a high-riding continental plate collides with a denser, heavier oceanic plate, the latter is pushed down into the fiery hot mantle. Its edge melts into magma or molten rock. This molten magma forces its way to the surface as volcano. The Andes Mountain range in South America and the Cascade Mountains in Washington State, Oregon, and California are volcanic ranges that were formed in this way. Evidences of The Continental Drift TheorySome of the evidences that are used to support the continental drift theory are the following: 1. Like a jigsaw puzzle, there is a near perfect match of the coastlines of distant continents, such as South America and Africa.2. Found in continents separated by oceans are identical remains of fossils of certain species of plants and animals.3. Coal deposits in Antarctica showed that this continent has experienced warm climate. That was the time when it was part of the supercontinent Pangaea.4. Identical rock formations were found on opposite shores of the Atlantic. This is proof that these shores were once part of the continent.5. North and South America continue to move away from Europe at the rate of 4 cm/year. India continues to move into Asia at the rate of 5 cm/year. As a consequence, Mount Everest and the Himalayan mountain ranges grow higher by 1 cm/year.