Mountain A large landform that stretches above the surrounding land in a limited area Mountains are formed through tectonic forces or volcanism Height from the surface of the earth by over ID: 435987
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Slide1
Mountain Building Slide2
Mountain
A large landform that stretches above the surrounding land in a limited area.
Mountains are formed through tectonic forces or volcanism.
Height from the
surface of the earth by over
1000
feet
(
300
m).Slide3
The term refers to the geological processes that underlie the formation of mountains. And the process is also known as orogenesis ,mountain building
.
Orogeny
It refers to forces and events leading to a large structural deformation of the Earth's lithosphere (crust and uppermost mantle) due to the engagement of tectonic plates.
Mountain Formation Slide4
Tectonic
geomorpholgy
& Neotectonics
The branch of science to understand landscape features in terms of underlying tectonic process is called Tectonic Geomorphology .
The field of study dealing with geological young or ongoing process is called Neotectonics.Slide5
Continental shield
Old mountains which are completely worn away and exist in form of flat regions .Slide6
Isostacy
Isostasy is the concept that Earth’s crust is floating in gravitational balance upon
the material
of the mantle.
Because of isostasy, deformed and thickened crust will undergo regional uplift both during mountain building and for a long period afterward.
Isostatic adjustment is the process of establishing a new level of gravitational equilibrium
.Slide7
Isostatic AdjustmentSlide8
Isostatic Adjustment in MountainsSlide9
Removal of material from the top will induce uplift at the surface. Removal of material from the bottom will produce subsidence. Thus, in the case of tectonic extension, isostasy will produce an effect that is opposite to thermal uplift.Slide10
TYPES OF MOUNTAIN
Volcanic mountains
Fault block mountains
Fold mountains
Uplifted/upward mountains, Dome MountainsNon boundary mountains
Residual MountainsSlide11
Volcanic mountains
Sheild
volcano
Composite /
strato volcanoMovements of tectonic plates create volcanoes along the plate boundaries which erupt and form mountains. A volcanic arc system
is a series of volcanoes that form near a
subduction
zone where the crust of a sinking oceanic plate melts.Slide12
Ocean-Ocean ConvergenceSlide13
Shield volcanoes can span across hundreds of miles
.Shield
volcanoes have a slow slope and consist of frozen lava after it is hardened. Shield volcanoes almost always have large craters at their summit
. gently sloping cone due to low viscosity of emitted material .(4-6 degree)
Shield volcano Slide14
Composite volcanoes have another name called “
Strato
Volcanoes.” Composite volcanoes consist of lava that is mixed with sand or gravel which in turn creates cinders or volcanic ash. steep rising cone due to high viscosity.(33 – 40 degree)
Composite volcano Slide15
Most volcanoes form along plate boundaries
Less common: forming over a hotspot (far from a plate boundary)
More than 400 volcanoes – 80% of all active volcanoes above sea level – are along
subduction
zones in the Pacific OceanActive = erupting or has erupted in recorded history“Ring of Fire”Slide16Slide17
Ocean-Continental ConvergenceSlide18Slide19
Fold MountainsSlide20
Fold Mountains
Fold mountains are mountains that are made when two of the earth’s plates collide.
When two plates collide the pressure compresses the rocks, forcing them to buckle and fold. Think of what happens to the bonnet of a car during a crash.Slide21
Fold MountainsSlide22
Convergence Slide23Slide24Slide25
Young Fold Mountains
As we know from previous sections, the earth’s plates are constantly colliding in different parts of the world. These collisions are still increasing the height of some fold mountains today.
The world’s young fold mountains are already about 30-35 million years old.
These mountains are called Alpine Fold Mountains. They are very high because they have not been worn down by weathering and erosion.Slide26
Alpine Fold Mountains
There are 4 major mountain ranges formed during the Alpine Folding period. These are,
1. The Rockies in North America.
2. The Andes in South America.3. The Alps in Europe.
4. The Himalayas in Asia.Slide27Slide28Slide29Slide30Slide31
Thrust faults main cause
Of folded mountainsSlide32
Large-scale normal faults are associated
with structures
called fault-block mountains
.
Fault-block mountains are formed as large blocks of crust are uplifted and tilted along normal faults.
Grabens
are formed by the downward displacement of fault-bounded blocks.
Horsts are elongated, uplifted blocks of crust bounded by faults.
Fault block mountains Slide33
Fault-Block MountainsSlide34
Alternating normal faults lead to a characteristic pattern called a
Horst and Graben system. An area under tension will often have
Multiple mountain ranges as a result.Slide35Slide36Slide37Slide38Slide39
Overthrust Faults
If the plate that suffers the fault has already undergone folding, & its folded layers are then push up & thrust over layers on the fault’s other side, an Overthrust Fault occurs.Slide40
Dome /uplifted Mountains
Dome mountains are the result of a great amount of melted rock (magma) pushing its way up under the earth crust.
Without actually erupting onto the surface, the magma pushes up overlaying rock layers. At some point, the magma cools and forms hardened rock. The uplifted area created by rising magma is called a dome because of looking like the top half of a sphere (ball). The rock layers over the hardened magma are warped upward to form the dome. But the rock layers of the surrounding area remain flat.
As the dome is higher than its surroundings, erosion by wind and rain occurs from the top. This results in a circular mountain range.
Domes that have been worn away in places form many
separate peaks called Dome Mountains. Slide41
Dome MountainsSlide42
Domed MountainsSlide43
Non-Boundary Mountains
Non-Boundary Mountains
Not all mountains are formed by plate boundaries. Some are formed by hot spots or regional extension or stretching.Slide44
Continental Accretion
Mountain Formation
Terranes
Terranes
are any crustal fragments that have a geologic history distinct from that of the adjoining fragments.
Accretion
is a process that occurs when crustal fragments collide with and stay connected to a continental plate.
Terranes occur along the Pacific Coast.Slide45
Mountain Building by
Continental AccretionSlide46
Residual Mountains
These are mountains that are really plateaus that have worn down from erosion
.Slide47