Rocks

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Rocks Minerals
I-Surface Materials A-Bedrock Soil 1-Crust
outer layer of earth consist of bedrock,
rock fragments, and soil.
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a-Bedrock- solid rock. When exposed to the
surface its called an outcrop. (range from
boulders to grains of sand) b-Soil- mixture of
small rocks, organic matter, air and water.
outcrop
Rock Fragments
Soil Rock fragments Bedrock
Bedrock
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B-Minerals 1-Rocks are composed of minerals,
which are naturally occurring solid substances
made of inorganic (nonliving) material. Minerals
have certain physical and chemical
properties by which they can be identified.
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• 1. Physical properties of minerals
• include streak color, hardness,
• luster, cleavage, and color.
• Luster refers to how a mineral looks
• when it reflects light. metallic, glassy,
  greasy,
• or earthy.
• Streak color is the color of the
• powdered form of the mineral.

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• Hardness resistance of a mineral to being
  scratched. Between I and 10, with I being softest
  and 10 the hardest.

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Mohls Hardness Scale
Hardness Mineral Test
1 Talc Finger Nail
2 Gypsum Will Scratch
3 Calcite copper penny will scratch
4 Fluorite Glass will
5 Apatite Scratch
6 K-felspar Steel
7 Quartz knife
8 Topaz Will
9 Corundum Scratch
10 Diamond Will Scratch all
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• Cleavage is a mineral's tendency to break along
  smooth, flat surfaces. Often causes a mineral
  to break into characteristic shapes.
• Color is not always a reliable guide to a
• mineral's identity.

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2. Minerals have chemical properties, how they
react with an acid. For example, calcite,
the chief mineral in limestone and
marble, fizzes when hydrochloric acid is
placed on it.
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C-Rocks natural, stony materials composed of
one or more minerals. Like minerals, rocks
are identified by their physical and
chemical properties.
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• Three groups of rocks
• 1- Igneous rocks are produced by the cooling
  and hardening liquid rock.
• a-Melted rock
• Magma underground Lava on surface

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b-Types of Igneous rocks Igneous rocks that
form from rapid cooling of lava, called
volcanic rocks, contain tiny crystals.
-Basalt dark-colored volcanic rock
composed of small crystals. The closer the
magma is to the surface, the smaller the grain
(crystal) size. Obsidian, a glassy, no
individual grains.
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Igneous rocks that cools slow form large
crystals. Granite is a light-colored igneous
rock that contains large, easily visible mineral
grains.
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2- Sedimentary rocks form from particles called
sediments that pile up in layers. These sediments
may be small rock fragments or seashells.
Sedimentary rocks usually form underwater.
Ocean
Stream carrying sediment
Sedimentary rock
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Common Sedimentary Rocks
Rock Name Type of Sediment Place of Formation
Sandstone Sand grains Shallow waters near a shore pounded by waves
Shale Clay particles Deep, calm ocean waters lake bottoms
Limestone Tiny seashells Warm, shallow seas
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3- Metamorphic rocks are produced when either
igneous or sedimentary rocks undergo a change in
form caused by heat, pressure, or both.
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Igneous Rock
Solidification
Erosion
Deposition
Melting
Metamorphic Rock
Sediments
Metamorphism
Burial and Cementing
Heat and/or Pressure
Sedimentary Rock
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II Earth History A- Interpreting Rocks rocks
contain information about that area's past.
1-Sedimentary rocks indicates the area
was once covered by water. 2-Fossils in
sedimentary rocks tell of past life and the
environmental conditions
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3- Horizontally layered sedimentary rocks
are easy to interpret. The bottom layers are
the oldest, youngest layers are at the top
YOUNGEST
OLDEST
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FAULT
PRESENT DAY
INASION OF IGNEOUS ROCK
FOLDED ROCK
INVASION OF IGNEOUS ROCK
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B-Fossils remains or traces of organisms that
lived long ago. 1-Fossils form when a dead
plant, animal, or footprint in mud,
is covered by sediment that later
hardens into rock. a-Almost all fossils are
found in sedimentary rock
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Brachiopod
Trilobite
Footprint
Cephalopod
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C-Dating Rocks To determine the age of rocks,
scientists use a technique called 1Radioactive
dating. a. Rocks contain small amounts of
radioactive substances that change
(decay) into non-radioactive substances
at a definite rate. b. Using this technique,
scientists have been able to assign dates
to the Earth. c. Earth itself is about 4.5
billion years old.
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2-Relative Dating Section of sedimentary
rock oldest sediment is on the bottom and
the youngest is on the top. a. It only tells
us that one fossil is older than
another.
Trilobite is an index fossil tells about the age
of the rock layer .