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

2. Contents Definition Classification of Rocks Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks

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

4. Classification Of Rocks
There Are Three Main Types of Rocks.
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks

5. Kinds of Rocks

6. 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 earth’s 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)

7. Sedimentary Rocks
Sedimentary rocks are formed by the deposition of material at the earth’s 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)
Arenaceous:These 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.

8. 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 200*C and pressure of 1500 bars causing profound physical and chemical change. All the process takes place deep beneath the Earth’s surface. In this process the structure of existing rocks changes. Slate, schist, marbles hornfels, diamond are metamorphic rocks.