Plate Tectonics

The 1958 Lituya Bay Alaska Tsunami

One of the largest-known landslide-induced tsunamis struck Lituya Bay of southeastern Alaska on July 9, 1958. Lituya Bay is located about 150 miles (240 km) southeast of Juneau and is a steep-sided, seven-mile-(11-km-) long, glacially carved fjord with T-shaped arms at the head of the bay where the Lituya and Cril-lon Glaciers flow down to the sea. The glaciers are rapidly retreating, a rock spit known as La Chausse spit blocks the entrance to the bay, and a large island, Cenotaph Island, rests...

Mount Pele Martinique 1902

Chile Pelee Martinque Map

Martinique was a quiet, West Indian island first discovered by Europeans in the person of Christopher Columbus in 1502. The native Carib people were killed off or assimilated into the black slave population brought by the French colonizers to operate the sugar, tobacco, and coffee plantations, and they exported sugar beginning in the mid-1600s. The city of St. Pierre, on the northwest side of the island, became the main seaport, as well as the cultural, educational, and commercial center of...

Shaanxi China January 23 1556

The deadliest earthquake and mass-wasting event on record occurred in 1556 in the central Chinese province of shaanxi. Most of the 830,000 deaths from this earthquake resulted from landslides and the collapse of homes built into loess, a deposit of wind-blown dust that covers much of central China. The loess represents the fine-grained soil eroded from the Gobi desert to the north and west and deposited by wind on the great loess plateau of central China. Thus, this disaster was triggered by an...

Water Cycle

The global water cycle is one of the major drivers and reservoirs for other geochemical cycles on the Earth. The water cycle describes the sum of processes operative in the hydrosphere, a dynamic mass of liquid continuously on the move between the different reservoirs on land and in the oceans and atmosphere. The hydrosphere includes all the water in oceans, lakes, streams, glaciers, atmosphere, and groundwa-ter, although most water is in the oceans. The hydro-logic, or water, cycle encompasses...

Taconic Orogeny

Taconic Orogeny

The Taconic allochthons are a group of Cambrian through Middle ordovician slates resting alloch-thonously on the Cambro-ordovician carbonate platform. These allochthons are very different from the underlying rocks, implying that there have been substantial displacements on the thrust faults beneath the allochthons, probably on the order of 100 miles (160 km). The allochthons structurally overlie wild flysch breccias that are basically submarine slide breccias and mudflows derived from the...

Force of Tsunami Impact and Backwash

When tsunamis crash into coastal areas they are typically moving at about 22 miles per hour (35 km hr). The speed as the wave moves inland changes dramatically, decreasing to a few miles per hour (several km hr) over short distances, depending on the slope of the beach or shore environment and how much resistance the wave encounters from obstacles on shore. The force associated with a debris-laden wall of water 50-70 miles (80-120 km) wide moving inland at that speed is tremendous. As tsunamis...

Landslides in the Andes Mountains Nevados Huascaran Peru 1962 1970

The Andes, a steep mountain range in south America, are affected by frequent earthquakes and volcanic eruptions, are glaciated in places, and experience frequent storms from being close to the Pacific Ocean. All of these factors combine, resulting in many landslides and related mass-wasting disasters in the Andes. some of the most catastrophic land slides in the Andes have emanated from Nevados Huascar n, a tall peak on the slopes of the Cordillera Blanca in the Peruvian province of Ancash. In...

History of Levee Building on the Mississippi River

Mississippi River Widening 100 Miles

The Mississippi River is the longest river in the world and encompasses the third-largest watershed, draining 41 percent of the continental United States including an area of 1,245,000 square miles (3,224,550 km2). The river transports 230 million tons of sediment, including the sixth-largest silt load in the world. Before the Europeans came and began altering the river, this silt used to cover the flood-plains with this fertile material during the semiannual floods and carry more downriver to...

Summary

Streams are dynamic systems that represent a balance between the forces that drive the current and those that resist the flow. Channels have many different styles that form in response to a quasi equilibrium between the gradient, or slope, of the streambed, the discharge of the stream, the amount of sediment being transported, the roughness of the streambed, and the resistance of the bank to erosion. The stream may form one of three main types of channels in response to the relative...

Tambora Indonesia 1815

The largest volcanic eruption ever recorded is that of the Indonesian island arc volcano Tambora in 1815. This eruption initially killed an estimated 92,000 people, largely from the associated tsunami. The eruption sent so much particulate matter into the atmosphere that it influenced the climate of the planet, cooling the surface and changing patterns of rainfall globally. The year after the eruption is known as the year without a summer in reference to the global cooling caused by the...

Large igneous province flood basalt A

Large Igneous Province Andes

Large igneous province, also known as a continental flood basalt, plateau basalt, and trap, is deposits that include vast plateaus of basalts, covering large areas of some continents. They have a tholeiitic basalt composition, but some show chemical evidence of minor contamination by continental crust. They are similar to anomalously thick and topographically high seafloor known as oceanic plateaus and to some volcanic rifted passive margins. In numerous instances over the past several hundred...

Andes Tectonic Zonation

Rio Plata Craton

The Andean mountain chain is a 5,000-mile- (8,000km-) long belt of deformed igneous, metamorphic, and sedimentary rocks in western south America, running generally parallel to the coast, between the Caribbean coast of Venezuela in the north and Tierra del Fuego in the south. some sections are characterized by active volcanoes, others by their absence. Most of the Andes are located above the subducting Nazca plate except for the southern Andes, which are located above the subducting Antarctic...

Himalaya Mountains

Where Nanga Parbat Located

The Himalaya Mountains were formed during the Tertiary continent-continent collision between India and Asia and contain the tallest mountains, as well as those exhibiting the greatest vertical relief over short distances, in the world. The range extends for more than 1,800 miles (3,000 km) from the Kara-koram near Kabul, Afghanistan, past Lhasa, Tibet, to Arunachal Pradesh in the remote Assam Province of India. Ten of the world's 14 peaks that rise to more than 26,000 feet (8,000 m) are located...

History of gondwana

Gondwana History

Gondwana is the name given to the southern continents that amalgamated before they joined, as a group, to the northern continents of Laurentia to form Pangaea. Most of Gondwana was assembled in the period between 600 million and 400 million years ago, when many Archean cratons were joined together by suturing during closure of several ocean basins that lay between them, forming a series of orogenic belts across Africa, India, South America, Madagascar, Antarctica, and Australia known as the...

Driving Forces Of Mass Wasting

Gravity is the main driving force behind mass-wasting processes, as it is constantly attempting to force material downhill. On a slope, gravity can be resolved into two components, one perpendicular to the slope, and one parallel to the slope. The steeper the angle of the slope, the greater the influence of gravity. The effect of gravity reaches a maximum along vertical or overhanging cliffs. The tangential component of gravity tends to pull material downhill, resulting in mass wasting. When gt...

Panafrican belts and the

Amazon River Gondwana Supercontinent

The East African orogen encompasses the Arabian-Nubian shield in the north and the Mozambique belt in the south. These and several other orogenic Map of the East African orogen and other Pan-African belts that formed as ocean basins closed to form the supercontinent of Gondwana (modeled from T. Kusky, M. Abdelsalam, R. Tucker, and R. Stern, 2003) belts are commonly referred to as Pan-African belts, recognizing that many distinct belts in Africa and other continents experienced deformation,...

Processes Of Mass Wasting

Mass movements are of three basic types, distinguished from each other by the way that the rock, soil, water, and debris move. slides move over and in contact with the underlying surface, while flows include movements of regolith, rock, water, and air in which the moving mass breaks into many pieces that flow in a chaotic mass movement. Falls move freely through the air and land at the base of the slope or escarpment. A continuum exists between different processes of mass wasting, but many...

December 26 2004 Indian Ocean Tsunami

December 2004 Tsunami

One of the deadliest natural disasters in history unfolded on December 26, 2004, when a great undersea earthquake with a magnitude of 9.0 triggered a tsunami that devastated many coastal areas of the Indian Ocean, killing an estimated 283,000 people. The Sumatra-Andaman earthquake had an epicenter located 100 miles (160 km) off the west coast of Sumatra, and struck at 7 58 a.m. local time. This was a very unusual earthquake, in that the rupture (and quake) lasted between eight and 10 minutes,...

Barringer Meteor Impact Crater Arizona

The Barringer Meteor Crater Arizona

One of the most famous and visited impact craters in the United States is the Barringer meteor impact crater in Arizona, the first structure almost universally accepted by the scientific community as a meteorite impact structure. The crater is 0.75 miles (1.2 km) across, and has an age of 49,000 years before present. Its acceptance as an impact crater did not come easily. The leading proponent of the meteorite impact model was Daniel Barringer, a mining company executive who argued for years...

Divergent plate boundaries in continents

Continents Divergent

Rifts are elongate depressions formed where the entire thickness of the lithosphere has ruptured in extension. In these places the continents are beginning to break apart as immature divergent boundaries, and if successful, may form new ocean basins. The general geomorphic feature that initially forms is known as a rift valley. Rift valleys have steep, fault-bounded sides, with rift shoulders that typically tilt slightly away from the rift valley floor. Drainage systems tend to be short,...

Aravalli Craton

The Aravalli craton is located in the northwestern part of peninsular India, bounded on the north by the Himalaya Mountain chain, the Cambay graben in the southwest, and the Narmada-Son lineament on the south and southeast. Young sediments cover the western boundary and may extend farther into Pakistan. Rocks of the Aravalli craton are quite different from the Dharwar and other cratons of the Indian shield. They consist mostly of Proterozoic phyl-lites, graywackes, quartzites, and carbonates,...

The 1992 Flores Indonesia Tsunami

One of the more deadly tsunamis in recent history hit the island of Flores, located in Indonesia several hundred miles from the coast of northern Australia near the popular resort island of Bali. The tsunami hit on December 12, 1992, and was triggered by a magnitude 7.9 earthquake, with the earthquake faulting event lasting for a long 70 seconds. The tsunami had run-up heights of 15 to 90 (4-27 m) feet along the northeastern part of Flores Island, where more than 2,080 people were killed and at...

Archean Cratons

Kapverdische Inseln

Archean rocks form the core of the Australian continent and include the cratonic nuclei of the Yilgarn, Plibara, Gawler, and Kimberly cratons. Archean rocks may also underlie portions of some of the Pro-terozoic basins and orogens, but less is known about the rocks at great depths in Australia. The Pilbara craton, located in northwestern Australia, contains mainly low- to medium-grade Archean rocks with the metavolcanic and metasedi-mentary rocks confined to relatively narrow belts between...

Tidal Inlets

Tidal Inlet Coastal

Tidal inlets are breaks in barrier island systems that allow water, nutrients, organisms, ships, and people easy access and exchange between the high-energy open ocean and the low-energy back-barrier environment consisting of bays, lagoons, tidal marshes, and creeks. Most tidal inlets are within barrier island systems, but others may separate barrier islands from rocky or glacial headlands. Tidal inlets are extremely important for navigation between sheltered ports on the back-barrier bays and...

Survey Of Impact Craters On Earth And The Moon

Map Largest Known Crater Earth

Impact craters are known from every continent including Antarctica. Several hundred impact craters have been mapped and described in detail by geologists, and some patterns about the morphology, shape, and size of the craters have emerged from these studies. The most obvious variations in crater style and size are related to the size of the impacting meteorite, but other variations depend on the nature of the bedrock or cover, the angle and speed of the impact, and what the impactor was rock or...

Coastal Deserts

Some deserts are located along coastlines, where intuition would seem to indicate that moisture should be plentiful. The driest place on Earth is the Atacama Desert, however, located along the coast of Peru and Chile. The Namib Desert of southern Africa is another coastal desert, known legendarily as the skeleton Coast, because it is so dry that many of the large animals that roam out of the more humid interior climate zones perish there, leaving their bones sticking out of the blowing sands....

Earthquake Magnitude

Earthquake Watchers

Earthquakes vary greatly in intensity, from unde-tectable ones up to ones that kill millions of people and wreak total destruction. For example, an earthquake in 2008 killed at least 90,000 people in China, yet several thousand earthquakes that do no damage occur every day throughout the world. The energy released in large earthquakes is enormous, up to hundreds of times more powerful than large atomic blasts. strong earthquakes may produce ground accelerations greater than the force of...

Trade wind or hadley cell deserts

Many of the world's largest and most famous deserts are located in two belts between 15 and 30 North and south latitude. Included in this group of deserts are the sahara, the world's largest desert, and the Libyan Desert of North Africa. Other members of this group include the Syrian Desert, Rub' al-Khali (Empty Quarter), and Great Sandy Desert of Arabia the Dasht-e-Kavir, Lut, and Sind of southwest Asia the Thar Desert of Pakistan and the Mojave and Sonoran Deserts of the united States. In the...

Baltic Shield on the Kola Peninsula

The Kola Peninsula occupies 50,000 square miles (129,500 km2) in northwestern Russia as an eastern extension of the scandinavian peninsula, on the shores of the Barents Sea, east of Finland and north of the White Sea. Most of the peninsula lies north of the Arctic Circle. The peninsula is characterized by tundra in the northeast, and taiga forest in the southwest. Winters are atypically warm and snowy for such a northern latitude because of nearby warm Atlantic Ocean waters, and warm summers...

SODIUM cycle

One of the most important geochemical cycles is the sodium cycle. sodium is one of the major constituents of crustal rocks, sediments, and ocean water, and moves from each of these reservoirs to the other over long geological times. sodium is dissolved from crustal rocks such as granite by rainwater, then streams and rivers carry it in solution to the sea. sodium (Na) and chlorine (Cl) are the two most abundant elements carried in solution in ocean water. They combine to form the mineral halite...

Explain Strata And Gravitational Eruption

Mount Helens Plate Boundary Map

One of the deadliest natural disasters in history unfolded on December 26, 2004, when a great undersea earthquake with a magnitude between 9.0-9.3 triggered a tsunami that devastated many coastal areas of the Indian ocean, killing an estimated 283,000 people. The tsunami devastated large parts of coastal Indonesia such as Banda Aceh, then swept across islands in the Indian ocean to strike Sri Lanka, India, and east Africa. The tsunami propagated into all of the world's oceans where it was...

Ural Mountains

The boundary between Europe and Asia is typically taken to be the Ural Mountains, a particularly straight mountain range that stretches 1,500 miles (2,400 km) from the Arctic tundra to the deserts north of the Caspian Sea. Naroda (6,212 feet 1,894 m) and Telpos-Iz (meaning nest of winds, 5,304 feet 1,617 m) are the highest peaks, found in the barren rocky and tundra-covered northern parts of the range. Southern parts of the mountain range rise to 5,377 feet (1,639 m) at Yaman-Tau, in the...

Subdisciplines Of Modern Astronomy

One relatively newer goal of modern astronomy is to describe and characterize objects in the distant universe, with the Milky Way galaxy being recognized as a distinct and related group of stars only in the 20th century. This realization was followed by recognition of the expansion of the universe as described by Hubble's law, as well as distant objects such as quasars, pulsars, radio galaxies, black holes, and neutron stars. The field of observational astronomy is based on data received from...

Precession Nutation

Precession Nutation

The chances of experiencing a large meteorite impact on Earth are small, but the risks associated with large impacts are extreme. Small objects hit the Earth many times every day but burn up in the atmosphere. Events that release enough energy to destroy a city happen about once every thousand years, while major impacts that can significantly alter the Earth's climate happen every 300,000 years. Truly catastrophic impacts that cause mass extinctions, death of at least 25 percent of the world's...

Granitic Magma

Granitic magmas are very different from basaltic magmas. They have about 20 percent more silica, and the minerals in granite include quartz (Si02) and the complex minerals mica (K,Na,Ca) (Mg,Fe,Al)2 AlSi4 O10 (OH,F)2 and amphibole ((Mg,Fe,Cah (Mg,Fe,Al)5 (si,Al)8 o22(oH)2), which both have a lot of water in their crystal structures. Also, granitic magmas are found almost exclusively in regions of continental crust. From these observations it is inferred that the source of granitic magmas is...

Collapsing Interstellar Cloud Fragment

Beautiful Stellar Cloud With Protostars

As the huge interstellar cloud collapses into many fragments, it is useful to consider the processes inside one of the individual cloud fragments as it continues to develop into a star. Most of these fragments are about one to two solar masses but can be about 100 times the size of the Earth's present solar system. The temperature of the cloud is about the same as when it started to condense, but it would have an increased density of about 1012 particles per cubic meter in the center of the...

Carbon Cycle

The carbon cycle preserves a record of many processes on the Earth throughout the planet's history and includes many geologic, biologic, ocean, and atmospheric systems. Many volatile substances including water and carbon dioxide were degassed from the deep interior of the Earth during the early Archean, and some has been added by cometary and meteorite impact. The early atmosphere of the Earth was rich in carbon dioxide (C02), and since the Archean this C02 has been progressively removed by the...

Internal Energy Sources Heat Transfer And Flow From Deep In The Earth

In geology crustal heat flow is a measure of the amount of heat energy leaving the Earth from internal energy sources, measured in calories per square centimeter per second. Typical heat-flow values are about 1.5 microcalories per centimeter squared per second, commonly stated as 1.5 heat flow units. most crustal heat flow is due to heat production in the crust by radioactive decay of uranium, thorium, and potassium. heat flow shows a linear relationship with heat production in granitic rocks....

Siberian Craton Aldan And Anabar Shields

East Russian Craton

The Siberian craton has Archean crust exposed in the Aldan and Anabar shields and in some of the Pha-nerozoic fold belts that surround the craton. Much of the craton is covered by thick platform sediments, and these are also underlain by Archean crust. The Aldan shield contains a gneissic and migma-titic basement deformed into large oval gneiss domes. Granulite facies gneisses, known as the Aldan Supergroup, have yielded ages of 3.4 to 3.2 billion years old. Interspersed greenstone and schist...

Bending Of Rocks

The bending or warping of rocks is called folding. Monoclines are folds in which both sides are horizontal, which often form over deeper faults. Anticlines are upward-pointing arches that have the oldest rocks in the center, and synclines are downward-pointing arches, with the oldest rocks on the outside edges of the structure. Though many other geometric varieties of folds exist, most are variations of these basic types. The fold hinge is the region of maximum curvature on the fold, whereas...

Cenozoic Tectonics And Climate

Cenozoic global tectonic patterns are dominated by the opening of the Atlantic ocean, closure of the Tethys Ocean and formation of the Alpine-Himalayan Mountain System, and mountain building in western North America. Uplift of mountains and plateaus and the movement of continents severely changed oceanic and atmospheric circulation patterns, altering global climate patterns. As the North and South Atlantic Oceans opened in the Cretaceous, western North America was experiencing contractional...

Bandediron Formation

Banded-iron formations are a distinctive type of sedimentary rock that formed predominantly dur ing the Precambrian and is the major source of the world's iron reserves. Banded-iron formations (BIFs) are a thinly bedded, chemically precipitated, iron-rich rock, with layers of iron ore minerals typically interbedded with thin layers of chert or microcrystal-line silica. Many are completely devoid of detrital or clastic sedimentary input. Most banded-iron formations formed between 2.6 and 1.8...

Thera Greece 3650 years before Present

Location Map Thera

One of the greatest volcanic eruptions in recorded history occurred approximately 3,650 years ago in the eastern Mediterranean region, then the cradle of civilization. Santorini is a small, elliptically shaped archipelago of islands, approximately 10 miles (16 km) across, located about 70 miles (110 km) north of the island of Crete. The islands are dark and ominous in stark contrast to the white limestone of the Greek islands, and they form ragged, 1,300-foot (390-m) peaks that seem to point up...

Kaapvaal Craton South Africa

Cratons Africa

The Archean Kaapvaal craton of southern Africa contains some of the world's oldest and most intensely studied Archean rocks, yet nearly 86 percent of the craton is covered by younger rocks. The craton covers approximately 363,000 square miles (585,000 km2) near the southern tip of the African continent. The craton is bordered on the north by the highgrade Limpopo mobile belt, initially formed when the Kaapvaal and Zimbabwe cratons collided at 2.6 billion years ago. On its southern and western...

Du Toit Alexander 18781948 South African

Geologist Alexander Du Toit, known as the world's greatest field geologist, was an early supporter of the theory of continental drift proposed by German meteorologist Alfred Wegener. Du Toit is credited with extensive mapping of the rocks sequences deposited on the Gondwana supercontinent and was one of the first scientists to knowledgeably correlate sequences between different continents. Alexander Du Toit was born on March 14, 1878, near Cape Town and attended school at a local diocesan...

Barrier Islands

Beach Subenvironments

Barrier islands are narrow linear mobile strips of sand up to about 30-50 feet (10-15 m) above sea level, and typically form chains located a few to tens of miles offshore along many passive margins. They the 6-12 foot (2-4 m) deep depression with up to 25 feet (8 m) of water and leave a path of destruction where the torrents of water raged through the city. These levees also channel the sediments that would naturally get deposited on the flood plain and delta far out into the Gulf of Mexico,...

Characteristics Of The Crust

Earth's crust is divisible broadly into continental crust of granitic composition and oceanic crust of basaltic composition. Continents comprise 29.22 percent of the surface, whereas 34.7 percent of Earth's surface is underlain by continental crust (continental crust under submerged continental shelves accounts for the difference). The continents are in turn divided into orogens, made of linear belts of concentrated deformation, and cratons, the stable, typically older interiors of the...

Subduction subduction zone

Plate Tectonics New Orleans

Principal axes remain perpendicular, but some other lines will be lengthening with each increment, and others will be shortening. There are some orientations that experience shortening first, and then lengthening. This leads to some complicated structures in rocks deformed by simple shear for instance, folds produced by the shortening, and then exten-sional structures, such as faults or pull-apart structures known as boudens, superimposed on the early contractional structures. Natural strains...

Periodic Table of the Elements

Periodic Table With Isotopes Amu

Numbers in parentheses are atomic mass numbers of most stable isotopes. Numbers in parentheses are atomic mass numbers of most stable isotopes. (g) none (c) semimetallics element symbol an. boron B 5 (g) pnictogen (c) metallics element symbol a.n. (g) none (c) semimetallics element symbol an. boron B 5 (g) pnictogen (c) metallics element symbol a.n. a n. atomic number (g) group (c) classification * semimetallics (c) ** nonmetallics (c) *** coinage metal (g) **** precious metal (g)

Liquefaction

Liquefaction is a process in which sudden shaking of certain types of water-saturated sands and muds turns these once-solid sediments into slurry with a liquidlike consistency. Liquefaction occurs where the shaking causes individual grains to move apart, then water moves up in between the individual grains, making the whole water sediment mixture behave like a fluid. Earthquakes often cause liquefaction of sands and muds. Any structures built on sediments that liquefy may suddenly sink into...

Foreland Basins

Foreland basins are wedge-shaped sedimentary basins that form on the continentward side of fold-thrust belts, filling the topographic depression created by the weight of the mountain belt. Most foreland basins have asymmetric, broadly wedge-shaped pro files with the deeper side located toward the mountain range, and a flexural bulge developed about 90 miles (150 km) from the foothills of the mountains where the deformation front is located. The indo-Gangetic plain on the south side of the...

Singhbhum Craton

The Singhbhum craton is located in eastern India, bounded by the Mahamadi graben and Sukinda thrust fault in the south, the Narmada-Son lineament in the west, the Indo-Gangetic Plain in the north, and the Bay of Bengal in the east. The craton has three main parts the old Archean Singhbhum nucleus in the south, the 2.2- to 1.0-billion-year-old Singhbhum-Dhalbhum mobile belt north of this, and the Chotanagpur-Satpura belt of gneisses and granites north and west of the mobile belt. The Singhbum...

Chemical Weathering

Minerals that form in igneous and metamorphic rocks at high temperatures and pressures may be unstable at temperatures and pressures at the Earth's surface, so they react with the water and atmosphere to produce new minerals. This process is known as chemical weathering. The most effective chemical agents are weakly acidic solutions in water. Therefore, chemical weathering is most effective in hot and wet climates. Rainwater mixes with Co2 from the atmosphere and from decaying organic matter,...

Acadian Orogeny

The Acadian orogeny has historically been one of the most poorly understood aspects of the regional geology of the Appalachians. Some of the major problems in interpreting the Acadian orogeny include understanding the nature of pre-Acadian, post-Taconic basins such as the Kearsarge-Central Maine basin, Aroostook-Matapedia trough, and the Connecticut Valley-Gaspe trough. The existence and vergence of Acadian subduction zones is debated, and the relative amount of post-Acadian strike-slip...

Rocky Mountains

Extending 3,000 miles (4,800 km) from central New Mexico to northwest Alaska in the easternmost Cordillera, the Rocky Mountains are one of the largest mountain belts in North America. The mountains are situated between the Great Plains on the east and a series of plateaus and broad basins on the west. Mount Elbert in Colorado is the highest mountain in the range, reaching 14,431 feet (4,399 m). The continental divide is located along the rim of the Rockies, separating waters that flow to the...

Aurora aurora borealis aurora australis

Earth Magnetic Field Aurora

Auroras Borealis and Aurora Australis are glows in the sky sometimes visible in the Northern and Southern Hemispheres, respectively. They are informally known as the northern lights and the southern lights. The glows are strongest near the poles, and originate in the Van Allen radiation belts, regions where high-energy charged particles of the solar wind that travel outward from the Sun are captured by the Earth's magnetic field. The outer Van Allen radiation belt consists mainly of protons,...

Different Types Of Supernovas

Enough supernovas have been observed to characterize some differences between them. Some supernovas have very little hydrogen associated with them (called Type-I supernovas), whereas others are hydrogen-rich (Type-II supernovas) and are associated with the star collapse or implosion described above. These two types of supernovas that have observationally different luminosity vs. time curves also have fundamentally different origins. A Type-I supernova, also known as a carbon-detonation...

Bam Iran 2003 magnitude

Iran sits in the zone of convergence between the Arabian and Asian plates and has numerous mountain ranges that formed by folding and faulting of the rocks in the collision zone. There are many earthquakes in Iran, some of which are extremely destructive and have killed many people. For instance, in 893 an earthquake in Ardabil Iran killed an estimated 150,000 people, and other deadly earthquakes have stricken most regions of Iran, including the capital, Tehran. On December 26, 2003, the...

Further Reading

Pine Creek Inlier

Meteorology Today. 7th ed. Pacific Proterozoic The Proterozoic refers to the younger of the two Precambrian eras and the erathem of rocks deposited in this era. Divisions of the Proterozoic include the Early or Paleoproterozoic (2.5 Ga-1.6 Ga), Middle or Mesoproterozoic (1.6 Ga-1.3 Ga), and Late or Neoproterozoic (1.3 Ga-0.54 Ga). Proterozoic rocks are widespread on many continents, with large areas preserved especially well in North America, Africa and Saudi Arabia, South...

Admired And Honored

Beginning in 1962 Hess chaired the Space Science Advisory Board of the National Academy of Sciences. The board's responsibility was to advise NASA. In 1966 he was at Woods Hole, Massachusetts, chairing a meeting to discuss the scientific objectives of lunar exploration when he began having chest pains. He died of a heart attack on August 25, 1969, and was buried at the Arlington National Cemetery. Hess was elected to membership of several academic societies including the National Academy of...

Formation Of Solar System

South America Map

The solar system began to form from a spinning solar nebula about 5 billion years ago, 9 billion years after the universe started expanding from nothing in the big bang some 14 billion years before the present. This solar nebula consisted of a mass of gas, dust, and fragments that began spinning faster as gravitational forces caused the material to collapse on itself. Temperatures ranged from extremely hot in inner parts of the solar nebula to cold in the outer reaches. Planets began accreting...

Final Years

The new grand duke hired Steno to tutor his 11-year-old son. Then in 1675 Steno was ordained and took a vow of poverty. The pope appointed him a bishop in 1677. The last years of his life were fairly dismal. In 1684 he wrote the pope, pleading for a release from his obligations. He wanted to return to Florence, where his days had been happiest. he was officially granted his request, but right before leaving he was asked to make a detour to help strengthen a new church in schwerin....

Sichuan Province China May 12 2008

The devastating magnitude 7.9 earthquake in the Longmenshan ranges of Sichuan Province, China, triggered thousands of landslides, including several gigantic landslides that buried several villages and blocked the Qingshui and Hongshi Rivers, forming two lakes, in Donghekou and Shibangou. Two of the first scientists to reach and study the Donghekou landslide after the earthquake were the British geologist Jian Guo Liu and the American geologist T. M. Kusky, who estimated the volume of material...

Plate Motion Sphere

Convergent Boundary Map

Dott. Evolution of the Earth. 6th ed. Boston McGraw-Hill, 2002. Windley, Brian F. The Evolving Continents. 3rd ed. Chichester, England John Wiley & Sons, 1995. photosynthesis Green plants, algae, and some bacteria trap solar energy and use it to drive a series of chemical reactions that results in the production of sugars, such as glucose, in a process called photosynthesis. The resulting sugars form the basic food for the plant as well as for insects and...

Reef Systems

Norman Bowen

Reefs are wave-resistant, framework-supported carbonate or organic mounds generally built by carbonate-secreting organisms, or in some usages the term may be used for any shallow ridge of rock lying near the surface of the water. Reefs contain a plethora of organisms that together build a wave-resistant structure to just below the low-tide level in the ocean waters and provide shelter for fish and other organisms. The spaces between the framework are typically filled by skeletal debris, which...

Seismograph

Rus Formation Evaporites

Seismographs are sensitive instruments that can detect, amplify, and record ground vibrations, especially earthquakes, producing a seismogram. Numerous seismographs have been installed in the ground throughout the world and form a seismograph network, monitoring earthquakes, explosions, and other ground-shaking events. The first very crude seismograph was constructed in 1890. While the seismograph could tell that an earthquake was occurring, it was unable to actually record the earthquake....

Central Gneissic Unit Tokwe Terrane

What Younger The Dike Intrusion

Three and a half billion-year-old gneissic and greenstone rocks are well exposed in the area between Masvingo (Fort Victoria), Zvishavane (Shabani), and Shurugwi (Selukwe), in the Tokwe segment. The circa 3.5-3.6 billion-year-old Mashaba tonalite forms a relatively central part of this early gneissic terrane, The Great Dike, a 2.5 billion-year-old magmatic intrusion in Zimbabwe, seen from the space shuttle Endeavour during mission STS-54, January 13-19, 1993 (NASA Photo Researchers, Inc.) and...

Water Politics and the Middle East

Tectonic Plate Boundaries Grid

Water shortage, or drought, coupled with rapid population growth provides for extreme volatility in any region. In the Middle East water shortage issues are coupled with long-standing political and religious differences. The Middle East, stretching from North Africa and the Arabian Peninsula, through Israel and Lebanon to Turkey, and along the Tigris-Euphrates valleys, has only three major river systems and a few smaller rivers. The population stands at about 160 million. The Nile has an annual...

Further Resources

Natural Disasters. 3rd ed. Boston McGraw-Hill, 2002. A college freshman-level book about natural disasters, listing causes and examples. Abrahams, A. D., and A. J. Parsons. Geomorphol-ogy of Desert Environments. Norwell, Massachusetts Kluwer Academic Publishers for Chapman and Hall, 1994. This is a comprehensive textbook, describing the wide range of landforms and processes in desert environments. Ahrens, C. D. Meteorology Today, An Introduction to Weather, Climate, and the...

Types Of Satellite Imagery

Satellite imagery forms one of the basic tools for remote sensing. The types of satellite images available to the geologist, environmental scientist, and others are expanding rapidly, and only the most common in use are discussed here. The Earth Resources Technology Satellite (ERTS-1), the first unmanned digital imaging satellite, was launched on July 23, 1972. Four other satellites from the same series, later named Landsat, were launched at intervals of a few years. The Landsat spacecraft...

Polar Deserts

A final class of deserts is the polar desert, found principally in the Dry Valleys and other parts of Antarctica, parts of Greenland, and northern Canada. Approximately 3 million square miles (7.8 million km2) on Earth consists of polar desert environments. in these places cold downwelling air lacks moisture, and the air is so dry that the evaporation potential is much greater than the precipitation. Temperatures do not exceed 50 F (10 C) in the warmest months, and precipitation is less than...

Processes Of Ophiolite And Oceaniccrust Formation

The sequences of rock types described above result from a specific set of processes that occurred along the oceanic-spreading centers where the ophiolites formed. As the mantle convects and the astheno- sphere upwells beneath mid-ocean ridges, the mantle harzburgites undergo partial melting of 10-15 percent in response to the decreasing pressure. The melts derived from the harzburgites rise to form a magma chamber beneath the ridge, forming the crustal section of the oceanic crust. As the magma...

Types Of Volcanism In Different Arcs

The most essential part of an island arc is the volcanic center, consisting of a line of volcanic islands comprising volcanic and pyroclastic debris, forming a linear chain about 60-70 miles (100-110 km) above the subducting slab. In island arcs the volcanic rocks are generally of several different types called volcanic series. These include a tholeiitic series, consisting of tholeiitic basalt, andesite, and less common dacite. The calc-alkaline series has basalts rich in alumina, abundant...

History Of ExPloration Of The Worlds Ocean Basins

What Are Ocean Basins Plate Tectonics

The earliest human exploration of the oceans is poorly known, but pictures of boats on early cave drawings in Norway illustrate Viking-style ocean vessels known to be used by the Vikings centuries later. Other rock drawings around the world show dugout canoes, boats made of reeds, bark, and animal hides. Early migrations of humans must have utilized boats to move from place to place. For instance, analysis of languages and of genetics shows that the Polynesians moved south from China into...

Yellowstone hot spot

Inside Hurricane Eye Wall

The northwest corner of Wyoming and adjacent parts of Idaho and Montana were established as Yellowstone National Park in 1872 by President Ulysses S. Grant, and it remains the largest national park in the conterminous united States. The park serves as a large nature preserve and has large populations of moose, bear, sheep, elk, bison, numerous birds, and a diverse flora. The park sits on a large upland plateau resting at about 8,000 feet (2,400 m) elevation straddling the continental divide....

Bhandara Craton

The Bhandara craton is located in the north-central part of the Indian subcontinent, bounded on the east by the Eastern Ghats, the Godavari rift and Dec-can basalts on the southwest, the Aravalli craton under the Deccan basalts and younger sediments to the northwest, and the singhbhum craton to the northeast. The craton consists largely of granites and gneisses with many inclusions of older sedimentary and volcanic rocks, overlain by several Late Proterozoic basins, including the Chhattisgarh...

Atmospheric evolution

Polar Front Cell

Considerable uncertainty exists about the origin and composition of the Earth's earliest atmosphere. Many models assume that methane and ammonia dominated the planet's early atmosphere, instead of nitrogen and carbon dioxide, as it is presently. The gases that formed the early atmosphere could have come from outgassing by volcanoes, from extraterrestrial sources (principally cometary impacts), or, most likely, both. Alternatively, comets may have brought organic molecules to Earth. A very large...

Cenozoic Geology Of Northern Arabian Plate Kuwait

Archean Earth Map

Kuwait is located in the northwest corner of the Arabian Gulf between 28 30' and 30 north latitude, and 46 30' to 48 30' east longitude. It is approximately 10,700 square miles (17,818 km2) the extreme north-south distance is 120 miles (200 km), the east-west distance is 100 miles (170 km). To the south it shares a border with Saudi Arabia to the west and north, it shares a border with Iraq. The semiarid climate of Kuwait is characterized by two seasons a long, hot, humid summer, and a...

Supernovas And The Formation Of The Heavy Elements

Supernovas are fundamentally important for life and the state of the universe, since nearly all of the elements heavier than carbon are formed in massive stars, and the elements heavier than bismuth 209 are all formed in supernova explosions. Only the elements hydrogen and helium are primordial in the universe, meaning that they have been in existence since the earliest moments of the universe. All of the other elements have been produced by nucleosynthesis, or the combination of large atomic...

Krakatau Indonesia 1883

Indonesia has seen catastrophic volcanic eruptions and associated tsunamis other than from Tambora. The island nation of Indonesia has more volcanoes than any other country in the world, with more than 130 known active volcanoes. These volcanoes have been responsible for about one-third of all the deaths attributed to volcanic eruptions and associated tsunamis in the world. Indonesia stretches for more than 3,000 miles (5,000 km) between southeast Asia and Australia, is characterized by very...

Scientific ContnBUTIONS

Coral Reefs

After completing his studies, Nicolaus Copernicus returned to Prussia and took on the position of secretary to his uncle Lucas Watzenrode, who was at the time the bishop of Warmia. During this time he lived at the bishop's castle at Lidzbark Warminski (Heilsberg) and started his research on the heliocentric model of the universe. Copernicus obtained a position as a burgher of Warmia in the Collegiate Church of the Holy Cross in Wroclaw (Breslau) in Bohemia, and he kept this position for most of...

Darwins Theory Of EvOLUTION

When Darwin returned to London he was already a celebrity in some scientific circles, since his mentor Henslow had shared many of his geological notes and biological findings with colleagues. After visiting family and friends Darwin returned to Cambridge and studied his notes, data, and samples with the help of many colleagues and scientists recommended by Henslow. Together they cataloged his collections from around the world and discussed many of the possibilities suggested by his geological...

Preference Of Geology Over

Charles Lyell was the oldest of 10 siblings, born November 14, 1797, at the family estate, Kinnordy, at Kirriemuir, in the county of Angus, Scotland. His mother's maiden name was Frances Smith, and his father, Charles senior, was a wealthy lawyer who enjoyed collecting rare plants. His family moved to Hampshire, England, when Charles was an infant. At the age of seven he was sent to the first of several English schools and graduated at the top of his class in June 1815. When he was 11 he...

Intrusive rocks

Bouclier Arabo Nubien

Intrusive rocks that cut the Arabian shield are divided into three main groups, called (from oldest to youngest) Pre-orogenic, syn-orogenic, and Post-orogenic. The preorogenic intrusions cut through the lower-layered rocks unit only and not the other layered rock units. They are considered older than the middle-layered rock unit but younger than the lower-layered rock unit. These intrusions are characterized by their calcic to calc-alkaline composition. They are dominated by gabbro, diorite,...

Slave Craton

Plate Tectonics Climate

The Slave craton is an Archean granite-greenstone terrane located in the northwestern part of the Canadian shield. The Archean history of the craton spans the interval from 4.03 billion years ago, the age of the world's oldest rocks, known as the Acasta Gneisses exposed in a basement culmination in the Wopmay orogen, to 2.6-2.5 billion years ago, the age of major granitic plutonism throughout the province. The margins of the craton were deformed and loaded by sediments during Proterozoic...

Core Of North America

Most of the core of North America was assembled by the collision of Archean cratons in the Paleoprotero-zoic, between 2.5 and 1.6 billion years ago. Paleo-magnetic data from the slave, superior, Churchill, and Wyoming cratons all show relative convergence of thousands of miles (up to 4,000 km) in the Late Paleoproterozoic, and wide collisional orogens developed between these cratons. At this time the Churchill Province consisted of the previously joined Rae and Hearne Provinces, and probably...

Geostrophic Currents

Plate Tectonics Climate

Some currents in the oceans follow specific horizons on the topographic contours of the ocean basin, staying at the same depth for long distances. These currents in the ocean or atmosphere, in which the horizontal pressure is balanced by the equal but opposite Coriolis force, are known as geostrophic currents. Friction does not affect these currents, which flow to the right of the pressure gradient force along pressure Map showing major cold and warm ocean currents of the world isobars in the...

Caspian Sea Trapped Oceanic Crust

Map The Caledonides

The Caspian is a large, shallow, salty inland sea, located between southern Russia, Kazakhstan, Turkmenistan, iran, and Azerbaijan. it is 144,444 square miles (373,000 km2), and its surface rests 92 feet (28 m) below sea level. it has a maximum depth of only 3,280 feet (1,000 m) in the south and is very shallow in the north, with an average depth of only 16.5 feet (5 m). Thus changes in the sea level bring large changes in the position of the shoreline. These historical changes in shoreline...

IvErgent Plate Boundaries In The Oceans The Midocean Ridge System

Yellowstone Death Zone

Some continental rifts may evolve into midocean ridge-spreading centers. The world's best example of where this transition can be observed is in the Ethiopian Afar, where the East African continental rift system meets juvenile oceanic spreading centers in the Red Sea and Gulf of Aden. Three plate boundaries meet in a wide plate boundary zone in the Afar, including the African Arabian boundary (Red Sea spreading center), the Arabian Somalian boundary (Gulf of Aden spreading center), and the...

Iceland Hot Spot

The mid-Atlantic ridge rises above sea level on the North Atlantic island of Iceland, lying 178 miles (287 km) off the coast of Greenland and 495 miles (800 km) from the coast of Scotland. Iceland has an average elevation of more than 1,600 feet (500 m), and owes its elevation to a hot spot interacting with the midocean ridge system beneath the island. The mid-Atlantic ridge crosses the island from southwest to northeast and has a spreading rate 1.2 inches per year (3 cm yr), with the mean...

Devonian strata

Sagar Siddiqui Poetry

In the late silurian and Devonian a major regression affected most of the craton, exposing the underlying rocks to subaerial erosion, except for a few deep basins and narrow seaways. This major unconformity is overlain by a new transgressive sequence known as the Kaskaskia sequence, which, like the two preceed-ing sequences, is marked by a basal quartz sandstone, overlain in turn by a thick carbonate sequence. Much of the continent was again covered by carbonate and shale deposition, and areas...

Pelagic nektonic planktonic

Bosmina Zooplankton

Color-enhanced micrograph of the crustacean zooplankton Bosmina longicornis (Christian Gautier Photo Researchers, Inc.) amount of air in their bodies, thus getting the nutrients they require and avoiding becoming food for predators. other plankton utilize their transparency or live in large schools of similar organisms to avoid being eaten. Phytoplankton are microscopic floating photo-synthetic organisms that form an extremely important part of the biomass and food chain. Examples include...

Siberian Taiga Forest And Global Carbon Sink

The northern third of Asia, stretching from the Ural Mountains in the west to the Pacific coast into the east, is known as siberia. The southern border of Siberia is generally taken to be the Kazakh steppes in the southwest, the Altai and sayan Mountains in the south, and the Mongolian steppes in the southeast. This region occupies approximately 3,000,000 square miles (7,500,000 km2). The western third of Siberia is occupied by the Siberian lowland, stretching from the Urals to the Yenisei...

Geomorphology

Yunnan Guizhou Plateau

China is geomorphologically diverse, consisting of about 33 percent mountains, 25 percent plateaus (including Tibet), 20 percent basins, and 10 percent hilly terrain. In general, the land surface slopes from the high regions including Tibet in the west, to the 1,100-mile (1,800-km) coastline in the east. Satellite image of Asia (M-Sat Ltd. Photo Researchers, Inc.) There are three main physiographic provinces of China based on elevation. The Tibetan, or Qinghai-Xizang Plateau, in the south rises...

Storm Surges and Bangladesh

The area that seems to be hit by the most frequent and most destructive storm surges is Bangladesh. A densely populated, low-lying country, Bangladesh sits mostly at or near sea level between India and Myanmar. It is a delta environment, built where the Ganges and Brahmaputra Rivers drop their sediment eroded from the Himalaya Mountains. Bangladesh is frequently flooded from high river levels, with up to 20 percent of the low-lying country being under water in any year. It also sits directly in...

Flash Floods

Flash floods result from short periods of heavy rainfall and are common near warm oceans, along steep mountain fronts in the path of moist winds, and in areas prone to thunderstorms. They are well known from the mountain and canyon lands of the U.S. desert Southwest and many other parts of the world. Some of the heaviest rainfalls in the United States have occurred along the Balcones escarpment in Texas. Atmospheric instability in this area often forms along the boundary between dry desert air...

Do bay of bengal cyclones have to be so deadly

Officials estimate that more than 100,000 people perished from tropical cyclone Nargis that hit Myanmar on May 2, 2008. Ninety-five percent of buildings in the coastal region were destroyed by the 12-foot (3.7-m) high storm surge, and more than a million were made homeless and without access to electricity, clean water, or medical care for many months following the disaster. When Cyclone Nargis blew into coastal Myanmar on May 2, it was unfortunately not the first time in recent years that a...

Indogangetic Plain

The Indo-Gangetic Plain is the active foreland basin of the India-Asia collision, with sediments derived from erosion of the Himalaya Mountains and carried by numerous rivers that feed into the Indus and Ganges Rivers. Alluvial deposits of the Indo-Gangetic Plain stretch from the Indus River in Pakistan to the Punjab Plain in India and Pakistan, to the Haryana Plain and Ganges delta in Bangladesh. Sediments in the foreland basin extend up to 24,500 feet (7,500 m) thick over the basement rocks...

Life In The Precambrian

The earliest known fossils are found in 3.5 billion-year-old cherts of the Warrawoona Group at North Pole, Australia. The fossils consist of stromatolites that formed reeflike mounds made of small, single-celled organisms called cyanobacteria, which are still common today. Stromatolites are known from many other Archean locations, and they are essentially the only macro-scale fossil found in Archean rocks. There are a variety of microscopic organisms known, but most of these fall into varieties...

Introduction

Folding Faulting Making Things

Encyclopedia of Earth and Space Science is a two-volume reference intended to complement the material typically taught in high school Earth science and astronomy classes, and in introductory college geology, atmospheric sciences, and astrophysics courses. The substance reflects the fundamental concepts and principles that underlie the content standards for Earth and space science identified by the National Committee on Science Education Standards and Assessment of the National Research Council...