WHAT IS A ROCK?

ORIGIN OF ROCKS

CLASSIFICATION OF ROCKS

3 basic types of rocks:

¯ Igneous

¯ Sedimentary

¯ Metamorphic

Overview:

Different types of rocks

Try this out:

Rock Quiz

ROCK test

Different types of weathering:

¯ Physical

¯ Chemical

¯ Biological

Factors affecting rate of weathering

Effects of Weathering on Rocks

Overview: Types of weathering and Weathered Rocks

ROCKS

1. WHAT IS A ROCK? 

2. ORIGIN OF ROCKS  

Rock cycle is a natural process that illustrates how rocks change from one form to another.

The process generally takes a long time.

Animation: Rock Cycle

Test your knowledge on Rock cycle (experiment):

Quiz 1

3. CLASSIFICATION OF ROCKS           [Back to top]

I.  IGNEOUS ROCK

Igneous rocks make up 95% of the rocks of the crust of Earth.

They are also some of the oldest rocks that are found at the surface of Earth.

Igneous rocks are sub divided into two types of classifications: extrusive and intrusive.

  Animation: Formation of Igneous Rocks (Intrusive and Extrusive) 

  Rock examples:

Intrusive: (molten rock cools before it reaches the surface)

granite

scoria

gabbro

   Extrusive: (molten rock reaches and cools on the earth's surface)

basalt - Basalt is a common gray to black volcanic rock. It is usually fine-grained due to rapid cooling of lava on the Earth's surface.

obsidian

pumice

andesite 

rhyolite

  For more detailed information on intrusive and extrusive igneous rocks

II. SEDIMENTARY ROCK

4 characteristics of sedimentary rocks:

have layers

have rock particles (formed from fragments of other rocks) e.g. conglomerate

have fossils

have crystalline appearance

Animation: Formation of Clastic sedimentary rocks

Formation of sedimentary rocks: 2 ways:

I. Layering

      Animation: Formation of sedimentary rocks  

         Rock examples:

sandstone

shale

jasper

II. Crystallization

       Evaporites - The evaporites form from the evaporation of water (sea water)

         Types of evaporites:

           Ä Rock salt- composed of NaCl (sodium chloride)

                 Salt Flats of Great Salt Lake, Utah

                 Salt deposits from evaporation and crystallizes

  Ä Rock gypsum - composed of gypsum (CaSo4H20)

                 Layered gypsum, New Mexico

                 gypsum crystals, Australia

                 gypsum1 , gypsum2

           Ä Travertine - composed of Calcium Carbonate (CaCo3)

                 limestone

for photo: Shows an area of layered sedimentary rocks

to investigate on The Different Types of Sedimentary rocks

III. METAMORPHIC ROCK

Metamorphic rocks are rocks that have changed shape or   composition due to intense heat and pressure.

(similar to the animation movie shown on the right)