Rocks

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Rocks

• Presented to Ms. Ayesha Saleem
• Presented By Ghulam Shabbir
• M.Sc Gegraphy 1st Semester(Roll No.6154)

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Contents

• Definition
• Classification of Rocks
• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks

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Definition

• Any naturally formed mass of mineral matter, of
  organic or Inorganic origin, that forms the
  earths crust, Is called a Rock
• All the hard part of earths crust is called
  rock, whether it is hard like granite, and soft
  like clay or chalk. (P.Lake)

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Classification Of Rocks

• There Are Three Main Types of Rocks.
• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks

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Kinds of Rocks
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Igneous Rocks

• Igneous Rocks are formed when molten magma cools.
• There are three main types of igneous rocks
• Intrusive igneous Rocks Form from magma that
  cools and solidifies within the interior parts of
  crust. (such as Granite)
• Hypabyssal igneous Rocks Form from the magma
  that cools in the rift zones of pre existing
  rocks. (such as Sill, Dyke, and Laccoliths)
• Extrusive igneous rocks form at the earths
  surface as a result of partial melting. These are
  fine grains because these solidifies more quickly
  than intrusive igneous rocks. (Such as Andesite,
  Basalt, Diorite, Gabbro and Scoria)

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Sedimentary Rocks

• Sedimentary rocks are formed by the deposition of
  material at the earths surface and within bodies
  of water. These are deposited in layers as
  strata, forming a structure called bedding. These
  can be subdivided into two groups
• Organic These rocks are called calcareous and
  carbonaceous rocks as they have significant
  amount of organic material of calcium and carbon
  (coal, oil and shale are their examples)
• Inorganic Argillaceous and Arenaceous are
  sub-types of inorganic rocks.
• Argillaceous These rocks contains particles of
  muddy matrix of clay and feldspar in abundance.
  (Gypsum, Rock Salt and Potassium)
• ArenaceousThese rocks contains more particles of
  Quartz, and sand grains. Calcium and silica
  cement these particles. Conglomerate, Sand stone
  and Silt stone are examples of these rocks.

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Metamorphic Rocks

• Metamorphism means change in form. Metamorphic
  rock is the transformation of an existing rock
  type. Metamorphic rocks are formed under high
  pressure and high temperature greater than 150
  to 200C and pressure of 1500 bars causing
  profound physical and chemical change. All the
  process takes place deep beneath the Earths
  surface. In this process the structure of
  existing rocks changes. Slate, schist, marbles
  hornfels, diamond are metamorphic rocks.