Chapter 1 Environment
Place people things and nature that surround any living organisms is called environment.
Combination of natural and human-made phenomena
Natural environment refers to both biotic and abiotic conditions
Natural environment Land water air plants and animals comprise the natural environment
Major domains of Earth with a sphere
Lithosphere
Hydrosphere
Atmosphere
Biosphere
What is ecosystem?
All plants animals and human beings depend on their immediate surrounding.
Also interdependent on each other
this relation between living organisms as well as relation between the organisms and their surrounding form an ecosystem.
Example large rain forest grasslands desert mountains Lake River ocean And even a small pond.
Human environment
Human being interact with environment and modify it according to their need.
Early humans adapted themselves to the natural surroundings
Led simple life and fulfilled the requirements from the nature around them.
A perfect balance is necessary between the natural and human environment.
Chapter 2 inside our Earth
Interior of the Earth
Earth is made up of several concentric layers.
Uppermost layer Called Crust
Thinnest About 35 on the Continental masses
and only five kilometer on the Ocean Floors.
Main mineral constituents-
Of Continental Mass are silica and aluminum(sial)
Oceanic crust consists of silica and magnesium(sima)
Just beneath the crust is the Mantle.
Extend up to two thousand nine hundred kilometer.
The innermost layer Core radius of about 3,500 kilometer made up of nickel and iron and is called nife.
Central core has very high temperature and pressure.
Rocks and minerals
Any natural mass of mineral matter that makes up the Earth's crust is called a rock.
Three major types of rocks-
igneous rocks
Sedimentary rocks
and metamorphic rocks
Igneous rocks when molten magma cools it becomes solid rocks.
Called primary rocks
Two types- intrusive and extrusive rocks
When molten lava comes on the surface rapidly cools down becomes solid- Called extrusive igneous rocks
Fine grain structure
Example basalt
Deccan Plateau made up of basalt rocks
Molten magma cools down deep inside Earth's crust Called intrusive igneous rocks
Since cool down slowly they form large grains.
Example granite
Grinding stones are made of granite.
Sedimentary rocks
Rocks roll down crack and hit each other and break down into small fragments called sediments.
Transported and deposited by wind water Etc.
These loose sediments compressed and hardened to form layers of rocks. Call sedimentary rocks.
Example sandstone
Made of grains of sand
Mainly contain fossil plants Animals
Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure.
For example Clay changes into slate Limestone into marble
One type of rock changes to another type under certain condition in a cyclic manner this process of transformation is known as rock cycle.
Rocks are made up of different minerals.
Minerals are naturally occurring substance, which have certain physical properties and definite chemical composition.
Chapter 3
Our changing Earth
Lithosphere is broken into a number of plates known as lithospheric plates.
These plates move around very slowly. Few millimeters each year. This is because of movement of molten magma inside the Earth(Moves in a circular manner)
Earth movements are divided on basis of force which causes them
Endogenous forces act in the interior of the Earth
Exogenic forces Forces that work on the surface of the Earth
Endogenic forces sometimes produce sudden movements
And sometimes slow movements
sudden movements like earthquakes and volcanoes.
Volcano Is a vent(Opening) In the Earth's crust through which molten material erupts suddenly.
Earthquake When lithospheric plates move
The surface of the Earth vibrates
Travel all around the earth these vibrations called earthquakes.
Place where movement starts called Focus Please on the surface of the focus is called the epicenter.
Vibrations travel outwards as waves
Earthquakes cannot be predicted some common earthquake prediction method adopted locally by people including studying animal behavior fish in the ponds get agitated snakes come to the surface.
Major landforms
Landscape is being continuously worn Away by two processes-
weathering and erosion
Weathering Breaking up of the Rocks erosion wearing away of the landscape by different agents like water wind and ice.
Eroded material carried away or transported by water wind and eventually deposited. This process of erosion and deposition create different landforms on surface of the Earth.
Work of a river
Running water in River erodes the landscape
When River tumbles at steep angle over very hard rocks. It forms a waterfall.
As the river enters the plane it twists and turns forming large bands known as Meanders.
Due to continuous erosion and deposition along the sides of the meander The ends of the Meander Loop come closer and closer.
In due course of time meander Loop cuts off from River and forms cut off Lake also called oxbow lake.
During floods Deposits layers of the fine soil and other material called sediment along its banks.
Formation of a flat fertile floodplain
The raised banks are called leeves.
As River approaches sea the speed decreases And river begins to break up into a number of streams called distributories
Each distributary reforms its own mouth The collection of sediments from all the mouths form Delta
Work of sea waves
Erosion of erosion and deposition of sea waves give rise to Coastal landforms.
See waves continuously strike at the Rocks
Cracks develop over time Become large and wider.
Hollow like caves are formed on the rocks called sea caves.
As this cavities become larger and bigger bigger only the roof of the caves remain thus forming see arches.
Further erosion breaks the roof only walls are left called stacks.
The Steep Rocky Coast Rising almost vertically above sea water which is called sea cliff.
Work of ice
Glaciers are rivers of ice which to erode the landscape by bulldozing soil and stones to expose the solid rock below.
Glaciers carve out deep Hollows As ice melts, they get filled up with water and become big beautiful lakes.
Material carried by glaciers such as rocks small sand and silt gets deposited these deposits- Form glacial moraines
Work of wind
Active agent of erosion and deposition in the deserts is wind.
Rocks in the shape of mushroom commonly called mushroom rocks Winds are eroded the lower section of the rock more than upper part.
Therefore such rocks are narrower base and wide tops.
When Wind Blows it lifts and transports and from one place to another.
Gets deposited in low heels like structure called sand dunes.
When grains of sand are very fine and Light. Wind carry it over very long distances. Such sand is deposited in large area. It is called Loess. Large deposit of Loess is found in China.
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