Transcript Erosion, Weathering and Rock Layers

Erosion, & Types of
Weathering
Chapter 10
Erosion
A process
where water,
wind, or
gravity
transports soil
(sediment)
from its
source
The process
by which rocks
are broken
down into
smaller pieces
There are 2
main types,
chemical &
Physical

Weathering
Mechanical Weathering

The break down of
rock into smaller
pieces due to physical
means
– Frost wedging (water
freezing in rock cracks)
– Abrasion (other rocks
or sediment rubbing
against rock.)
Chemical Weathering
 Rocks
break
as a result of
a chemical
change
– Acid rain
– Chemical
decomposition
– Gases in the air
(oxidation)
Deposition
 Is
the process
where
material lays
to rest
 Sediment
is
deposited in
bodies of water
and on land
Chapter 6
The Rock Record
Sedimentary Rock Layers
 This is a normal record of rock. Layers are
undisturbed. The Geologic Column is a
model of what rock layers should look like.

Uniformitarianism
A
principle or rule that states that
events that happened in the past can
be explained by current earth
(geologic) processes
 Earth Processes like erosion,
weathering, and deposition remain
uniformed and do not change.
Catastrophism
A
principle that states that
geologic changes happen
suddenly. (natural disasters)
 They believed the Earth was only
a few thousand years old.
 Catastrophic events formed the
Earth, created volcanoes,
mountains, oceans, etc.
Relative Dating
Determines
which comes
first. Determining if rock
layers are older or younger
Compare them to
undisturbed rock around the
world
Principle of Superposition
A principle or rule that
states that younger
rocks lie above older
rocks in un-disturbed
sequences
 As you move from top
of rock layers to the
bottom the rock
layers get older

SUPERPOSITION
Uplift
movement
within the
Earth that
moves rocks
to the
surface
Unconformities
Is a disturbance in the layer of a rock.
 Represents thousands, to millions of years
in missing time in the layers of a rock
 Can be created through:

– Erosion and weathering (p159, figure 4)
– Faulting- (earthquakes)
– Folding (anticlines, synclines, and monoclines)
– Tilting
– intrusion
Rock Intrusion
A layer of molten
rock (hardened
magma) from the
Earth’s interior that
squeezes into
existing rock and
then cools.
 Melts surrounding
layers
 Interrupts the rock
time scale.

Types of Unconformities

Disconformity – part of a parallel rock
layer is missing. (Layers may be eroded
away and deposited elsewhere)
Nonconformity- horizontal sedimentary
rock layers lay on the eroded surface of
intrusive igneous rocks or metamorphic
rocks
 Angular unconformity- rocks are tilted or
folded due to earthquakes or uplift (p 160)

Terms
 Erosion
 Weathering
 Uplift
 Deforestation
 Mechanical
weathering
 Chemical
weathering
 Relative
dating
 Uniformitarianism
 Superposition
 Intrusion
 Catastrophism
 Un-conformity
 Strip Mining
 Frost Wedging
 Abrasion