Environmental 3_gls684.pptx

ENVIRONMENTAL STUDIES (GLS684) TOPOGRAPHICAL ENVIRONMENTAL

Physical environmental Earth profile

Distribution of the movement of the earth's surface

Diastrophism • Diastrophism, also called tectonism, large-scale deformation of Earth’s crust by natural processes, which leads to the formation of continents and ocean basins, mountain systems, plateaus, rift valleys, and other features by mechanisms such as lithospheric plate movement (that is, plate tectonics), volcanic loading, or folding.

Sudden Movement • These movements cause considerable deformation over a short span of time, and may be of two types. • Volcanic – Volcanism includes the movement of molten rock (magma) onto or toward the earth’s surface and also formation of many intrusive and extrusive volcanic forms.

• Earthquake – It occurs when the surplus accumulated stress in rocks in the earth’s interior is relieved through the weak zones over the earth’s surface in form of Earthquake kinetic energy of wave motion causing vibrations

LITHOSFERA MOVEMENT Plate Tectonic Theory • all of the major movements of the earth crust movements that produce whether the movement vertically, horizontally or both simultaneously and also includes the processes of formation of the Earth's crust • The Earth's surface is divided into several lithosfera plate. These plates are constantly moving relative to each other. • plates collide or meet each other at the plate boundary • a meeting between the plates produces three types of plate boundaries – Transform boundary – Divergent boundary – Convergent boundary

Transform Boundary Fault Line A transform fault or transform boundary is a plate boundary where the motion is predominantly horizontal It ends abruptly and is connected to another transform, a spreading ridge, or a subduction zone

Divergent boundary When a divergent boundary occurs beneath oceanic lithosphere, the rising convection current below lifts the lithosphere, producing a mid-ocean ridge. Extensional forces stretch the lithosphere and produce a deep fissure. When the fissure opens, pressure is reduced on the super-heated mantle material below. It responds by melting, and the new magma flows into the fissure. The magma then solidifies and the process repeats itself.

Mid Ocean Ridges

sea level

Magma rises up

Convergent boundary Divide by two situation: 1. Subduction zone 2. Mobile belts

Subduction Zone •

Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle. • Plates include both oceanic crust and continental crust. Stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. • Usually have a high rate of volcanism and earthquakes • develop belts of deformation and metamorphism in the subducting crust, whose exhumation is part of orogeny and also leads to mountain building

Mobile belts

Major Lithospheric Plates

• • • • • •

Pacific Plate – 103,300,000 km2 North American Plate – 75,900,000 km2 Eurasian Plate – 67,800,000 km2 African Plate – 61,300,000 km2 Antarctic Plate – 60,900,000 km2 Indo-Australian Plate – 58,900,000 km2 often considered two plates: Australian Plate – 47,000,000 km. ... • South American Plate – 43,600,000 km2

TSUNAMI

What causes a tsunami?...

A tsunami is a large ocean wave that is caused by sudden motion on the ocean floor. •

This sudden motion could be : – an earthquake, – a powerful volcanic eruption, – or an underwater landslide.  The impact of a large meteorite could also cause a tsunami.  Tsunamis travel across the open ocean at great speeds and build into large deadly waves in the shallow water of a shoreline.

TSUNAMI Subduction Zones are Potential Tsunami stuck plate : Locations prevents a slow and steady rate of subduction and instead the two plates become "stuck."

The moving wave begins travelling out from where the earthquake has occurred. Some of the water travels out and across the ocean basin, and at landward to flood

continues to descend into the mantle, the motion causes a slow distortion of the overriding plate. The result is an accumulation of energy very similar to the energy stored in a compressed spring. Energy can accumulate in the overriding plate over a long period of time.

the overriding plate snaps back into an unrestrained position. This sudden motion is the cause of the tsunami - it gives an enormous shove to the overlying water.

ROCK CYCLE

• Understanding eksogen process • The solid material that form the earth's crust is rocks • rocks including soil, sand, minerals

Rocks Cycle

Igneous rock

Sedimentary rocks • Sedimentary rocks are formed by the accumulation of sediments. There are three basic types : – Clastic sedimentary rocks such as breccia, conglomerate, sandstone, siltstone, and shale are formed from mechanical weathering debris. – Chemical sedimentary rocks, such as rock salt, iron ore, chert, flint, some dolomites, and some limestones, form when dissolved materials precipitate from solution. – Organic sedimentary rocks such as coal, some dolomites, and some limestones, form from the accumulation of plant or animal debris.

Sendimentary Rocks

Metamorphic Rocks • Metamorphic rocks have been modified by heat, pressure, and chemical processes, usually while buried deep below Earth's surface. • There are two basic types: – Foliated metamorphic rocks such as gneiss, phyllite, schist, and slate have a layered or banded appearance that is produced by exposure to heat and directed pressure. – Non-foliated metamorphic rocks such as hornfels, marble, quartzite, and novaculite do not have a layered or banded appearance.

SOIL

Soil profile

Soil texture • Soil classification is typically made based on the relative proportions of silt, sand and clay

Soil

Soil erosion • soil transfer rate exceeds the rate of soil produced by the bedrock through weathering . • Erosion, whether it is by water, wind or tillage, involves three distinct actions – soil detachment, movement and deposition. • erosion is closely related to the climate, the topography of the area (the slope of the land), land surface conditions