the Ocearn Floor Volcanic Island When volcanoes on the ocean floor erupt, they can create mountains so high that their peaks break the surface of the ocean. As the lava cools and hardens, an island forms Mid-Ocean ridge The mid-ocean ridge consists of many peaks along both sides of a central valley. This chain of undersea mountains runs all around the world. Continental slope A steady indine marks the continental slope. Continental slopes in the Pacific Ocean are Continental shelf This gradually sloping area width varies from just a few 1,300 kilometers from shore. borders each arth's oceans are thousands of kilometers wide. To show the width of the ocean floor in this illustration, the vertical and horizontal steeper than those in the Atlantic Ocean. Note: Because the kilmeters to as much as vertical scale is exaggerated, the continental slope in this illustration appears steeper than it realy is scales are not the same. The vertical scale, showing depth, has been stretched. The horizontal scale, showing distances, has been squeezed. Continental shelf Continental slope Mountains whose peaks do not break the surface of the ocean 6 water above them are E called seamounts Abyssal plain Thick layers of sediment, formed by the sunken remains of dead organisms from the surface cover these vast, flat plains These canyons in- clude the deepest spots on Earth. The Mariana Trench in the Pacific is 11 kilometers deep. Width of ocean: thousands of kilometers
Rifting makes oceans widen Continental plate 20mm/year Rising material
MOR Mid Oceanic Ridge *Rising limb of current breaks the Ocean crust * Basaltic eruption * Accumulation of lava - ridge-> PlatePlate MOR *New Oceanic crust **Divergent limb - expansion of ocean crust. Oceanic ridges are underwater mountain ranges that contain a rift down their center where magma seeps up, forming new oceanic crust.
PaleoMagnetism is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. O This record provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates.
Oceanic ridges are underwater mountain ranges that contain a rift down their center where magma seeps up, forming new oceanic crust. The rocks formed from this underwater volcanic activity were mainly basalt, which is an iron-rich, volcanic rock that makes up most of the ocean floor. Basalt contains magnetic minerals and as the rock is solidifying, these minerals align themselves in the direction of the magnetic field. This basically locks in a record of which way the magnetic field was positioned at the time that part of the ocean floor was created. Scientists took a look at the ocean floor going out away from oceanic ridges, they found magnetic stripes that were flipped so that one stripe would be normal polarity and the next reversed. Reason: these oceanic ridges were actually boundaries with tectonic plates pulling apart. This movement of the plates allowed the magma to rise up and harden into new rock. As the new rock was formed near the ridge, older rock, which formed millions of years ago when the magnetic field was reversed, got pushed farther away, resulting in this magnetic striping.
TH AMER PLATE EURASIAN PLATE EURASIAN PLATE JUAN DE PLATE CARIBBEAN PHILIPPINE PLATE /PLATE ARABIAN PLATE cocos PLATE PLATE EGUATOR AFRICAN TE PACIFIC PLATE NAZCA PLATE AUSTRALI PLAT SOUTH AMERICAN PLATE AUST PLATE OTIA PLATE ANTARCTIC PLATE
Location of rocks Example Property Mantle Olivine Highly fluid; Heaviest BasaltFluid; Heavy Andesite Less mobile; Lighter Granite Least mobile; Lightest Oceanic crust Continental crust Continental crust
Divergent Plate Boundary Ascending limb of convection current - can be below Ocean or Continent. PlatePlate If Below ocean -> formation of MOR If Below continent ->rift valley, nascent sea
Divergent Plate Boundary Continental crust Oceanic crust - MOR Divo Cont Rilting A Upwarping New rock added to eachside of the mid-ocean ridge Continental Crust Mogma B. Rift valley ormed C. inear Sea Mid ocean Ridge Molten material Oceanic crust Oceanic Crust
Phases of Divergent continental crust Rift valley Basalt oruptions Continental- crust Mantle Rift valley Seawat River Fault -.. .. blocks Continental shelf Rift valley Sea level
The Great African rift valley ARABIAN PLATE Nile River AFRICAN PLATE Nubian) Erta Ale Gulf of Aden INDIAN PLATE Exjuator AFRICAN PLATE Somalian) oldoinyo Lengai Lake Victori Tang. aW EXPLANATION Plate boundaries East African Rift Zone
ETHIOPIA 150 3 0 4 SUDAN SOMALIA L. TURKANA UGANDA L ALBERT L KYOGA KENYA L VICTORIA L. TANGANYIKA TANZANIA D.R. CONGO L. M ALAWI / NYASSA MOZAMBIQUE ZAMBIA
IRAQ IRAN Prelims 2000 Which one of the following lakes form an international boundary between Tanzania and Uganda? a) Chad b) Malawi c) Victoria d) Zambezi Cairo LIBYA | EGYPT SAUDI A RA BIA CHAD SUDA/N ERITREA YEMEN Khartoum Grand Addis Ababa SOUTHMillennium Dam SUDAN) c. A. RN ETHIOPIA. UGANDA KENYA RWANDA BURUNDI INDIAN OCEAN 1,000 km ak Victoria TANZANIA
made of Continental volcanic arc Oceanic Crust Basalt. Trench Continental Crust Granite. Oceanic crust O So Oceanic crust is heavier and so it subducts under Continental Crust. And then it melts and then conversion of these Basalt rocks into Andesite and then it comes out via a explosive volcanoes. A volcanic mountain Chain will be formed on the Margin of that continental crust. ducting oceanic lit Continental lithosphere anic lithosphere t Metting Asthenosphere
Ocean ndia india
ARCTIC OCEAN Mountain Ranges of the World ASIA NORTH AMERICA EUROPE PACTFIC ATLANTIC 1. Arts OCEAN s OCEAN AFRICA PACIFTC OCEAN SOUTH AMERICA INDIAN OCEAN AUSTRALIA Great viding ATLANTIC OCEAN 1,000 2 ANTARCTICA
Importance of mountain building process Understanding of the origin and evolution of earth's crust. At the time of the formation of the earth crust, first basaltic crust of ocean - breaking and melting - a lighter continental crust developed Collide with one another a larger land mass. The joints - fold-mountains.
Mediserr ranean Sea Tibesti a Nubiarn Niger Guit of Hi Congo Co n itoriaIndian Ocean of Lake Tanganyik A t la nti Lake Malaw Plateau O c e a n Kalahari
Me ORU MTS ENS Gan 0 Plain ngeS rahmaputr Narmada E Deccan odi Mahanao Arabian Sea Gulfof
Seattle L S uron %Plateen-1 Black Hills Mi n Detroit Boston Chioago York ral (Lowlands . San Franciscbz Arkansas Washington DC Plateau APP ed River Los C oast a Hou New Orleans ston Guif of Mexic o
Basaltic eruption Andesitic eruption JOccur at mid-oceanic Volcanic arcs, volcanic mountains ridge and hot spot volcanism Basalt highly fluid- mobile JAndesite - less fluid less mobile Solidifies at short distance- intense pressure develop inside explosive Spread across easily Quite eruption
Intrusive Landforms *Intrusion of Magma in sedimentary rocks Sills (Horizontal) * Dyke (Vertical) Laccolith-magma which could not come out &Lopolith - saucer-shaped Phacolith-shape like waves Batholith-intrusive granitic rock
Shield/ dome Cinder Highly fluid ss fluid /highly F Silent flovw Gentle slope Steep slope Composite Fluid viscous viscous Violent eruption Multiple and violent eruption Highest volcanoes Small volcanoes Small volcanoes Large volcanoes
Geysers Geysers - fountains of Hot water . Ground water heated by shallow source of magma . Old faithful geyser, Yellow stone park, USA
Difference between geyser and HotSpring geyser *Geyser - Groundwater heated by hot spring shallow magma source *Hot spring - g/w heated by either magma source or heated rocks Geyser chamber in interior + pressure>comes out like fountain steam groundwater porou roc superheated water *Hot-spring - quite porous rock eat magma
Geyser Hot spring Found anywhere u Geysers are rare O Hot water dissolved with They gets different colors silica accumulated on surface - gives different colours from heat-loving bacteria, like cyanobacteria Medicinal values J USA, Yellowstone park Can be helpful in harness geo-thermal energy
B.Tech NIT Allahabad. Have written UPSC Mains 2 times with Physics. Channel "Sumant Kumar" on Youtube for Current Affairs Analysis.