I.Choose the correct answer:-
1._________ is theonly planet has organisms in it. Earth
2. The Pangea isbroken into —— major plates.7
3. The______________of the earth is not stable. Crust.
4. Large scalevertical movements of the earth crust are called ____________ movements. Endogenic.
5. The point oforigin of the earthquake is called Focus.
II.Fill in the blanks:-
1. The continentscrust is composed of granite layer.
2. The SIAL layeris floating on the SIMA layer.
3. Large scalehorizontal movements of the earth crust arecalled Endrogenic movements.
4. Surfaceis also known as L waves.
5. A volcano is a ventor an opening in the earth crust.
IIIMatch it:
1. Mauna loa –Hawai
2. Vesuvius – Italy
3. Kilimanjaro –Africa
4. Fujiyama – Japan
5. Norcondam –India.
IVAnswer the following:
1.Name the types of layers of the earth.
v Thecrust
v Themantle
v Thecore
2.Pangea:
v Afew million years ago all the present continents were clusterd together aroundSouth pole.
v Thissuper continent was called Pangea.
Panthalassa:
v ThePangea was surrounded by a mega ocean called panthalassa. Panthalassa wasotherwise known as Super Ocean.
3.Namethe major plates of the world.
v Eurasia,Antarctica, North America, Pacific, South America, Africa and Indo Australianplates.
4.Name the forces which affect the Earth movements.
v Endogenicor Internal forces: Such internal forces are earthquake volcano and landslide.
v Exogenicor External forces: Such external forces are river wind, glacier and sea waves.
5.Whatis mean by anticline and syncline?
v Horizontalmovements of the earth crust make folding and displacement of the layers ofrocks.
v Simplefolding consists of alternating upfolds called Anticlines and downfolds called synclines.
6.Whatare the types of volcanoes?
v Activevolcano
v Dormantvolcano
v Extinctvolcano.
VDistinguish between:
1.SIAL
v Thesontinental crust is composed of a layer.
v Itis made up of of silica and aluminium.
v Theaverage depth of sial is about 20 k.m.
SIMA
v Theoceanic crust is composed of basaltic layer.
v Itis made up of silica and magnesium.
v Theaverage depth of sima is about 25 k.m..
2.Crust
v Theupper most layer of the earths surface.
v Itis also called as lithosphere.
v Itis divided into sima and sial.
CORE
v Theinner most layer of the earth surface.
v Itis also called as Baryspere.
v Thisdivide into inner core and outer core.
3.Dormant
v Theyare called sleeping volcanoes.
v Thesevolcanoes have been active in the past stopped erecting lava now, but it canerupt at any time in the future. Eg. Vesuvius in Italy.
EXTINCT
v Theyare called dead volcanoes.
v Thesevolcanoes erupted in the past but they did not do so recently and in future itis expected there will not be any eruptions. Eg. Kilimanjaro in Africa.
4.Endogenic forces and exogenic forces.
v Itoriginates and acts from within the earths crust.
v Itgives rise to deformation and irregularities on the crust of the earth.
v Thesemovements which bring about vast changes on the crust of the earth.
v Itoriginates and acts on the surface.
v Itremoves the irregularities to made a leveled on and below the crust.
5.Primarywaves and secondary waves:-
v P-wavesmoves faster and are the first to be recorded by the seismograph.
v Itcan travels through gaseous liquid and solid materials.
v Ittravels at a speed of 8k.m./sec.
v S– Waves are slower than the P-waves.
v Itcan travel through solid materials.
v Ittravels at a speed of 5k.m./sec.
VI.Answer in briefly.
1.Name the layers of the earth and explain the crust in detail.
Layersof the earth
v Crustmantic core sial upper mantle upper core sima lower mantle lower core.
v Theuppermost layer of the earths surface is called the crust.
v Thecontinental crust is composed of a layer called the sial which is made up of silica and Aluminum.
v Theoceanic crust is composed of basaltic layer layer called the sima which is made up of silica andmagnesium.
v Crustis thicker on the continents and thinner in the ocean floor.
v Thesial layer is floating on the sima layer.
v Theaverage depth of sial is about 20 k.m.
v Theaverage depth of sima is about 25 k.m.
v Theaverage density of the crust is about 3gkm.
2.Describe the types of earthquakes waves.
Earthquake waves are divided into body waves and surface waves.
Bodywaves:-
Body waves areproduced by the release of energy at the focus and move in all directions.
These are two typesof body waves.
1.Primary waves orp-waves
2.Secondary wavesor s-waves.
Primarywaves:-
v P-wavesmove faster and are the first to be recorded by the seismograph.
v Itcan pass through gases, liquids and solids.
v Ittravels at a speed of 8k.m./sec.
Secondarywaves:-
v S-wavesare slower than the p-waves. It can travel through solid materials.
v Duringthe occurrences of secondary waves, particles oscillate in the directions ofwave travel.
v Ittravels at a speed of 5k.m./sec.
Surfacewaves.
v Thesewaves are the last to be recorded on the seismograph.
v TheseWaves cause most of the damages on the surface.
v Theyare called as L-waves.
v Theytravel at a speed of 4km/sec.