Post on 17-Jan-2016
Types of Rocks
Ms. Sikes
Igneous Rocks
• Form from magma
• 2 types:– Intrusive: (inside) rock formed
from magma beneath the earth’s surface–Extrusive: (outside) rock
formed as a result of volcanic activity at or near earth’s surface
Igneous Rocks cont…
• Texture is determined by how fast it cools. – Slow = coarse (bumpy) texture– Fast = fine (smooth) texture
Examples of Igneous RocksPUMICE
OBSIDIAN
GRANITE: the most abundant igneous rock
Sedimentary Rocks
• Formed when sediment (gravel, sand, mud, silt) forms layers and are compacted (smushed) together
• Forms at the earth’s surface (often in the bottom of lakes and oceans)
Sedimentary Rocks cont…• 3 types of Sedimentary Rocks:– 1. Clastic- made of rock fragments and
cemented together by a mineral like calcite or quartz (these look grainy) (sandstone)
– 2. Chemical- form from dissolved minerals in water (halite)
– 3. Organic- form from fossils of animals (coal)
Characteristics of Sedimentary Rocks
• Usually in layers (strata)
Examples of Sedimentary Rocks
• See page 373 in book
Metamorphic
• What does the word metamorphosis mean? Where have you heard it before?
Metamorphic Rocks
• Were originally sedimentary or igneous rocks
• Formed when: heat or pressure is different from what the rock is used to and it changes the rock
• Usually rocks change at temps between 50 degrees Celsius to 1000 degrees Celsius
Ways that rocks can metamorphasize
• 1. rock is heated by nearby magma
• 2. pressure builds up in rocks which causes it to change
Texture of Metamorphic Rocks
• Foliated: mineral grains are arranged in bands
• Nonfoliated: mineral grains are randomly arranged
Slate Marble
Picture tour of book
• Look on pages 369-380
Classify your rocks
• Which ones are sedimentary?
• Which ones are Igneous?
• Which ones are metamorphic?
• Can you name any of them?
Exit Ticket
• On a post it note:• Explain how each type of rock is
formed:• 1. metamorphic• 2. sedimentary• 3. igneous