Download Faults - Geology

Mountains
Part II
Domed and FaultBlock
Dome Mountains
Created when magma pushes
up from underneath existing
strata and cools.
Associated features:
A
sill is an igneous intrusion that
squeezes in between existing rock
layers
– Goes parallel to the layers
– The cliff band on Triangle Mtn is a sill
A
dike is similar but cuts across the
existing rock strata
– The belt on Mt Daly is a dike
Intrusive Magma:
Batholiths
are large bubbles
of magma (usually felsic) that
cool underground.
–Forms Tectonic Domes
Smaller
bubbles are called
Laccoliths- usually a sill that
has bulged upwards.
–Forms Plutonic Domes
Stock>
Domed mountains create:
 Cuestas
 Hogback
ridges
 Flatirons
 Watergaps
 Stocks
Dike
Dike
Mtn Sopris = Stock
Flat Irons- Boulder
Hogback- front range
- closest = Grand Hogback near Rifle
Cuesta- Horse tooth Reservoir
Historic photo of the Grand HogbackNew Castle
How to tell the difference between
a folded and a domed mountain?
 If
the mountain is folded, the
underlying rocks will be either
sedimentary or metamorphic
 If
the mountain is domed, then the
rocks below will be igneous
(intrusive/plutonic)
FaultBlock
Mountain
Fault Block Mtns

Formed from blocks of crust that have
been faulted and tilted at the same time.
Red Butte
 Sangre De Cristos
 Tetons
 Sierra Nevada
 Wasatch Mountains

Joints
Rock
layers may rupture
from pressure applied.
Fractures where no
movement has occurred
are called joints,
Faults
Faults
are fractures in the
earth’s crust where
movement has occurred.
There are three types:
normal, reverse or thrust,
and strike-slip (also called
transcurrent).
Teton Mountains
The
Tetons in Wyoming have
been uplifted along a fault
plane.
Mountain Ranges
Mountain
ranges are
formed when long belts of
the earth’s crust are folded
and/or faulted then are
uplifted and eroded. The
Rockies are an example.
Erosion
When
a section of the
earth’s crust is elevated,
streams begin to erode
deep channels.
Can form mountains
also.
Capstones
Resistant
layers help to
produce mesas, buttes,
and pinnacles.
Earthquakes
Earthquakes
occur
due to movement
along faults.
Lake Baikal-deepest lake in the world
-5,315 feet deep
-contains 1/5 of all the world’s freshwater
Lake Tahoe