Page 105 - General Knowledge

GENERAL KNOWLEDGE 2019

 These rocks are made up of the weathered remains of igneous rocks, but also contain
organic matter from the remains of marine organisms.
 Sedimentary rocks are formed in horizontal layers, called strata and take millions of years to
harden into rocks.
 These rocks are also known as stratified rocks because of these layers.
 Although three-fourths of the earth‘s surface is covered with sedimentary rocks, they make
up for only 5 per cent and get broken into fragments, further reduced into small particles
called sediments.

 These are derived from igneous, metamorphic or older sedimentary rocks.
 For this reason these are known as sedimentary or fragmental rocks.

Characteristics of Sedimentary Rocks
 These rocks are porous and they are stratified and without pores.
 They are affected by erosive forces easily.
 These rocks are formed by the rock sediments, fossils and vegetative material, so they
contain more calcareous and carbonaceous contents.
 They possess joints and stratification.
 The majority of the rocks of this type are formed by sedimentation on the floors of water
bodies.
 These rocks are easily breakable due to softness.
Metamorphic Rocks
 Change is the rule of nature.

 This change is also seen in rocks.
 Pressure and heat, bring a partial or whole change in rocks.
 Sometimes the physical properties of the original rock are entirely different from that of
newly formed rock.
 This type of change is known as the Metamorphism and the rocks formed by this process
are known as Metamorphic Rocks.
 The word Metamorphic is derived from the Greek word Metamorphosis, which means
change.
 This change is found in texture, colour, hardness, and mineral composition of rocks.
 This metamorphosis is brought about by the pressure and heat of the layer mass over each
other in Sedimentary and Igneous rocks.
Characteristics of Metamorphic Rocks
 These rocks are formed by intense pressure, heat and the chemical action over the rocks.
 They are formed by the metamorphosis in sedimentary and igneous rocks.
 They are formed in the solid state.
 They are formed at the depth of thousands of kilometers and there are no fossils in them.

Hydrosphere
 A hydrosphere is the total amount of water on a planet.
 The hydrosphere includes oceans, rivers and lakes. It also exists below ground as
groundwater, in wells and aquifers.

 Water vapor is most visible as clouds and fog.
 The frozen part of Earth‘s hydrosphere is made of ice: glaciers, ice caps and icebergs.

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