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Heading:
Geology
CLASSWORK #5
DIRECTIONS:
o Read the paragraphs below.
o Use the information in the paragraphs to answer questions 1-3.
1The first thing that we need to know about rocks is: rocks are created from minerals. When a liquid
magma/lava cools to a solid, the substance is said to have crystallized. This means as magma/lava cools, the
elements in the magma/lava form solid bonds with their neighbors in a repetitive (repeating) pattern. The
minerals form into bigger and bigger crystals until they smash into other crystals. Once enough mineral
crystals smash together so hard that they can't be taken apart, the minerals have formed into an igneous rock.
Great examples of these types of rocks are basalt and granite.
2Igneous
rocks are born in fire. There are two types of igneous rocks. The first type and most common is the
intrusive igneous rocks. These rocks form when a pocket of magma inside the earth slowly cools down enough
to form into solid rock. Granite is the most common intrusive igneous rock.
3Intrusive
igneous rock has coarse (large) grained crystals. That means, if you look closely at the rock you can
see the mineral crystal grains. If you look closely at a piece of granite you will see little flecks of white, black,
gray, and sometimes pink. These flecks of color are mineral crystal grains. If you can see the crystal grains that
form an igneous rock, you're looking at an intrusive igneous rock.
4The
second type of igneous rock is called extrusive igneous rock. When magma reaches the surface of the
earth it is called lava. Extrusive igneous rocks are formed when lava cools and forms into solid rock. This
cooling is much faster than the slow cooling that forms intrusive igneous rocks. Extrusive igneous rocks have
small crystal grains. Yes, they have crystals; they're just so small you usually can't see them. There are many
different types of extrusive igneous rocks. The type of igneous rock you get depends on what kind of lava the
rock was formed from, and how fast the rock cooled. Basalt is the most common extrusive igneous rock.
1. Which type of igneous rock cools quicker, outside the earth, giving it fine (small) mineral crystal grains?
A. Intrusive igneous rock
B. Extrusive igneous rock
Paragraph #: _____________
2. Does extrusive igneous rock form from magma or lava?
A. Magma
B. Lava
Paragraph #: _____________
3. Think about the temperatures inside the earth compared to the temperatures outside the earth. Why
do you think intrusive igneous rocks cool slower than extrusive igneous rock? (Write at least 2
sentences.) _________________________________________________________________________
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4. Complete the table below.
Type of Igneous
Magma or Lava
Rock
Inside Earth or
Outside Earth
Large Grains or
Small Grains
Cools Slowly or
Cools Quickly
DIRECTIONS:
o Complete the Venn Diagram below by writing in the clues provided in their appropriate bubbles.
o In the two outer circles, list characteristics of each that set them apart from each other.
o In the overlapping middle section, list characteristics that they have in common.
Igneous Rocks
Small mineral grains
Large mineral grains
Granite
Forms from melted material
Lava
Cools slowly
Magma
Formed outside the earth
Cools quickly
Basalt
Formed inside the earth
Intrusive Igneous Rocks
Extrusive Igneous Rocks