•Evolution of Earth •Distribution of Continents and Oceans •Latitudes and Longitudes World Map series: Lecture 1

Santosh Choudhary CSE 2018

Insta: little_simple_buddha

Plan :

• Formation of earth, continents and oceans

• Tectonic plates

• Longitudes, latitudes, prime meridian and international date line

• An overview of course

Formation of Earth

• In primordial stage the earth was in volatile stage, a ball of hot burning lava with a thin atmosphere.

• Due to gradual increase in density and temperature inside increased and consolidation of material of different density started.

• It allowed heavier material to sink to centre of earth and lighter ones to move towards surface.

• As the earth cooled down, further solidification and condensation took place and crust was formed.

• In the process of differentiation, earth forming material operated in different layers- crust,, mantle. Outer core and inner core.

• Alfred Wegener gave “Continental Drift” theory -

• All the continents formed a single continental mass, a mega ocean surrounded by the same.

• The super continent was named PANGAEA, which meant all earth.

• The mega-ocean was called PANTHALASSA, meaning all water.

• Around 200 million years ago, the super continent, Pangaea, began to split.

• Pangaea first broke into two large continental masses as Laurasia and Gondwanaland forming the northern and southern components respectively.

• Subsequently, Laurasia and Gondwanaland continued to break into various smaller continents that exist today -

• 7 continents Asia and Europe, North America, South America, Africa, Australia and Antarctica

• 5 oceans-Atlantic, Pacific, Indian, Arctic and Southern Ocean

Distribution of Continents and Oceans

• Plate tectonics is the theory that Earth's outer shell, Lithosphere, is divided into several major ad minor plates that glide over the mantle, the rocky inner layer above the core.

• Plates move horizontally over the asthenosphere, as rigid units.

• The thickness of lithosphere is about 200kms over continents and 5-200 kms over oceanic plates.

• Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries (or faults).

Tectonic Plates

Mantle convection drives plate tectonics. Hot material rises at mid-ocean ridges and sinks at deep sea trenches, which keeps the plates moving along the Earth’s surface

• Divergent Plate Boundary:

• Where new crust is generated as the plates pull away from each other. Ex. Mid-Atlantic Ridge

• Convergent plate Boundary:

• Where the crust is destroyed as one plate dived under another. The location where sinking of a plate occurs is called a subduction zone.

• There are three ways in which convergence can occur.

• between an oceanic and continental plate

• between two oceanic plates

• between two continental plates.

• Transform Plate Boundary:

• Where the crust is neither produced nor destroyed as the plates slide horizontally past each othe

Types of Plate Boundaries

1. Antarctica and the surrounding oceanic plate

2. North American (with western Atlantic floor separated from the South American plate along the Caribbean islands) plate

3. South American (with western Atlantic floor separated from the North American plate along the Caribbean islands) plate

4. Pacific plate

5. India-Australia-New Zealand plate

6. Africa with the eastern Atlantic floor plate

7. Eurasia and the adjacent oceanic plate.

Major Tectonic Plates

• An imaginary grid is used to find a location on globe. This grid is made up of imaginary lines called latitudes and longitude.

• Latitudes measures distance from north to south of the equator, starting from 0° and ending up with 90° to both sides of the equator, making latitude Northern and Southern.

• Longitude measures distance east to west. The longitude can be defined maximum as 180° east from the Prime Meridian and 180° west from the Prime Meridian. 0° is called Prime Meridian (Greenwich) line.

Latitude and Longitude

• Study all political maps- locations as in open to oceans/seas, landlocked, climate wise and relative location of countries and important cities .

• Important physical features such as mountain ranges, deserts, plains, plateaus , islands, straits, rivers, peninsulas, oceans , seas, bays etc

• Detailed study of India’s as political and physical map.

• Previous year questions including mock questions.

Approach for lecture series :