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Slide 1
The world of rocks; GeologyAn art of spying
Deepak C. Srivastava IIT Roorkee, Roorkee, Uttarakhand
What is Geology?Science of the Earth...just like chemistry and physics!What is different about Geology?Special challenge- controlled experiments?The rates of geologic processes are almost always slower than the rates of human effects on the environment.Geologists use millions of years as the standard unit of time:Some geologic features take millions of years to form.
Carr CliftonOthers take seconds
John Sanford/Photo Researchers5
Spying the signatures of nature
Objective?Ex. Rock type?
Types of signatures depend on origin of rocks3. Metamorphic2. Sedimentary1. IgneousThree types of origin:Magma- the molten rock material3 components:Liquid = meltSolids, if anyVolatiles = dissolved gasesIgneous originSolidification of magma Igneous rocks
Igneous rocks(Magma) Plutonic
(Lava) Volcanic
Surface
Deep or Shallow/surface?Glassy Texture
Lava or Magma?TextureGrain size?
Domestic Example?
Lava or Magma?
Interlocking textureLava or Magma?Igneous rocks?
Examples:Tin, Tungsten, Diamond, Platinum, mica. Weathering (Breaking)TransportationDeposition
Sedimentary rocks?Let us spy the evidence for these processes in rocks
Three componentsClastMatrixCement
Clast, Matrix, CementEaES 350-619
Sedimentary laryeringWhat happens when you go to?
Kashmir in wintersRajasthan in summers
Metamorphic rocksResults of Stress Compressive Stress
Shear StressCauses Foliation
21
Evidence of Metamorphism Differential pressure squashes rock and included features2. Flattened PebblesConglomerateMetaconglomerate22
Evidence of Metamorphism
23Any pre-existing rocks can be metamorphosed
Rock Cycle25