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Rocks
Elizabeth Riker, Aaron Mosesso, Mike Werhan, and
Abbi Smith
Classifications of Rocks
Sedimentary Rock
 Sediment rocks occur by
weathering, erosion and
transport because of wind
and water, sediments
become rock when they
get compacted.
 Common sedimentary
rocks are:
 Limestone
 Sandstone
 Conglomerate
Conglomerate
Igneous Rocks
 The Earth has magma deep
inside it. If the magma stays
underground, cools, and
hardens, it makes intrusive
igneous rock.
 Extrusive igneous rock is made
when magma comes to the
Earth’s surface in the form of
lava and then cools and hardens.
 Common igneous rocks are:
 Granite
 Basalt
 Diorite
Granite
Metamorphic Rocks
 Metamorphic rocks are formed
when other kinds of rocks are
changed by great heat and
pressure inside the earth.
 They were once indigenous or
sedimentary rocks but have
morphed over time.
 They are usually toward the
bottom of layers of rocks.
 Common Metamorphic rocks
are:
 Gneiss
 Schist
 Slate
Gniess
Stratigraphic Laws
Law of Superposition
•States that the oldest layer
of rock is at the bottom
and the youngest layer of
rock is at the top.
Law of Original Horizontality
•States that sediment o
rock layers were deposited
in a horizontal orientation.
•If units aren’t horizontal
an event occurred
subsequent to the
deposition which
caused layers to fold or
tilt.
Law of Lateral Continuity
•States
that deposits
originally extended in
all directions.
Law of Cross-Cutting Relationships
•States the relationship
between existing rock and
rock which intrudes by
magma flow into existing
rock.
•This creates and intrusion
and an intrusion is always
younger than the rock it
invades.