1. ALPHA COLLEGE OF ENGINEERING AND TECHNOLOGY
CIVIL A [3RD SEM ]
TOPIC :- TYPES OF ROCK AND ROCK CYCLE
GROUP 1O ENROLLMENT NO
DARSHAN R MEHTA
KOMAL N MALVANIYA
HARDIK G MAKWANA

2. Rocks and The Rock Cycle

3. What is a rock?
A rock is a mixture of such minerals, rock fragments, volcanic glass, organic matter, or other natural materials.
Most rock used for building stone contains one or more common minerals, called rock-forming minerals, such as quartz, feldspar, mica, or calcite
When you look closely, the sparkles you see are individual crystals of minerals.

4. How do Rocks form? How much time does it take to form a rock?
If you squeeze and heat a rock for a few million years, it can turn into a new kind of rock.

5. Continued… Where does the heat come from?
When rocks are close enough to the magma to be heated but not close enough to be melted, the rocks can be changed.

6. Continued… Where does the pressure come from?
Rocks below the surface are squeezed by the layers of rock above them. The thicker the layers, the more pressure there is.

7. What makes up the earth?

8. 3 Main Rock Types
Igneous
Sedimentary
Metamorphic

9. THE THREE TYPES OF ROCKS
Igneous rock is formed from molten rock that has cooled and hardened.
Sedimentary rock is formed from material that has settled into layers and hardened.
Metamorphic rock is a rock that has changed by heat and pressure.

10. Examples… Igneous Metamorphic Sedimentary Granite Slate Sandstone
Obsidian
Marble
Limestone
Pumice
Gneiss
Shale

11. IGNEOUS ROCKS
Form by solidification (crystallization) of melted minerals
At the surface, LAVA hardens to form EXTRUSIVE rocks with tiny (FINE-GRAINED) crystals or GLASSY (no crystal) TEXTURES
Beneath the surface, MAGMA hardens to form INTRUSIVE rocks with easily visible (COARSE-GRAINED) crystal texture.

12. Granite Light-colored, coarse- grained, no pattern
Mostly quartz, feldspar, mica, and hornblende
Often used for buildings and monuments

13. Basalt Dark-colored, fine- grained, extrusive
Formed where lava erupted onto surface
Most widespread igneous rocks
Found locally in the Palisades along west shore of Hudson River, Connecticut River valley

14. Gabbro Dark-colored, coarse- grained intrusive
Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine

15. Obsidian Natural volcanic glass Forms when lava cools very quickly
Usually dark, but small pieces may be clear
Fractures along curved (conchoidal) surface
Used as spear and arrow points, knives

16. Pumice and other igneous rocks
Light colored, frothy (many air spaces)
Same minerals as in granite, but finer in grain size

17. Igneous Forms when lava cools quickly on the Earths surface EXTRUSIVE
Forms from molten rock cooling and solidifying
Magma cools slowly over millions of years deep beneath the surface
INTRUSIVE

18. IGNEOUS---Extrusive Little or NO Crystals!
Lava cools on the surface so fast mineral do not get a chance to form
Extrusive rocks can be divided into two categories based on color
Dark colors black-brown-red
Basalt
Obsidian
Light colors white-gray-pink
Rhyolite

19. IGNEOUS---Extrusive Little or NO Crystals!
Lava cools on the surface so fast mineral do not get a chance to form
Extrusive rocks can be divided into two categories based on color
Dark colors black-brown-red
Basalt
Obsidian
Light colors white-gray-pink
Rhyolite

20. IGNEOUS---Extrusive Little or NO Crystals!
Lava cools on the surface so fast mineral do not get a chance to form
Extrusive rocks can be divided into two categories based on color
Dark colors black-brown-red
Basalt
Obsidian
Light colors white-gray-pink
Rhyolite

21. IGNEOUS---Extrusive Little or NO Crystals!
Lava cools on the surface so fast mineral do not get a chance to form
Extrusive rocks can be divided into two categories based on color
Dark colors black-brown-red
Basalt
Obsidian
Light colors white-gray-pink
Rhyolite

22. Igneous Forms when lava cools quickly on the Earths surface EXTRUSIVE
Forms from molten rock cooling and solidifying
Magma cools slowly over millions of years deep beneath the surface
INTRUSIVE

23. IGNEOUS---Intrusive Large Interlocking Crystals!!!
Magma cools slowly over millions of years…
LARGE CRYSTALS FORM
Intrusive rocks can also be divided into two categories based on color
Dark colors black-brown-green
Gabbro
Light colors white-gray-pink
Granite

24. 3 Main Rock Types
Igneous
Sedimentary
Metamorphic

25. Sedimentary Rocks
Sedimentary rocks may be made of rock fragments—sediments—or by chemical reactions. The classification of sediments is shown below.

26. How to make a sedimentary rock
Weathering and Erosion
Transportation
Deposition
Compaction and Cementation
Sedimentary Rock

27. Sedimentary Chemical Clastic Shale Sandstone Conglomerate
Sedimentary rocks are divided into two categories
Chemical
Mineral are dissolved in to the water…water is evaporated off and leaves behind chemical sedimentary rocks
Examples are Halite, Limestone and Gypsum
Clastic
Made from eroded fragments of other rocks
Shale
Microscope grains of mud cemented together
Sandstone
Sand grains cemented together
Conglomerate
Pebble to boulder size fragments cemented together

28. Clastic rocks–made of cemented sediments—are classified by their grain sizes.

29. Non-clastic rocks form by chemical precipitation (settling out from a solution.) Limestone is made from calcite, chert from quartz, and halite is rock salt.

30. Biologic sedimentary rocks come from the remains of organic matter.
The most important of these is coal. Anthracite coal results from the greatest pressure and releases the most energy when burned. Other varieties are bituminous and lignite. “Petrified” (permineralized) wood is another organic rock.

31. More about sedimentary rocks
Shale is the most common sedimentary rock
Sedimentary rocks cover about three-quarters of the land surface
For more about sedimentary rocks:

32. 3 Main Rock Types
Igneous
Sedimentary
Metamorphic

33. Metamorphic rocks form from HEAT&PRESSURE
Two types of metamorphism
Contact
Rock surrounding a magma body get cooked and changes due
Regional
Tectonic forces
Metamorphism occurs over a large area

34. Metamorphic Rocks Formed by heat and pressure changing existing rocks
REGIONAL METAMORPHIC affects a large area and results from plate tectonics
CONTACT METAMORPHISM affects rocks on a local scale, such as “baking” sedimentary rocks next to magma or lava

35. “Foliated” rocks contain much mica and other rocks that produce layering or banding
Gneisses and schists are common in New York City and Westchester.

36. Non-foliated metamorphic rocks include marble, which comes from limestone, and quatzite, which comes from sandstone

37. Common Metamorphic Rocks
Parent Rock
Metamorphic Rock
Granite
Gneiss
Shale
Slate
Sandstone
Quartzite

38. What is the rock cycle?
To show how rocks slowly change through time, scientists have created a model called the rock cycle.
It illustrates the processes that create and change rocks.

40. Here is another version of the Rock Cycle

41. The Rock Cycle

42. The Rock Cycle explains how Rocks and Natural Processes are related
weathering
Sedimentary
Metamorphic
Is the rock cycle really this simple, neat and colorful?
(NO)
Created October 2, 2000, revised September 2001
melting
pressure, heat
Igneous

43. The Rock Cycle
Sedimentary
Igneous
Metamorphic

44. Another Rock Cycle

45. Mohs Hardness Scale

46. Thank
you