....Folding
the crust forms mountains?
(...See? It's official - crumpling the crust forms mountains....)
....Folding
the crust forms mountains?
(...See?
It's official - crumpling the crust forms mountains....)
| "Colliding continents are
similar to colliding cars. If two cars run into each other, they crumple
where they meet. The same thing happens with continents; the crumples are
called mountains..."
"..What keeps building mountains
is not obvious ?...> but most mountains are pushed upward, their rock beds
wrinkled like bedsheets or tilted like stacks of newspapers. The
plates bump each other's edges in a slow-motion Demolition Derby, and that's
where mountain ranges get their start. ?.....> "Mountain belts
are typically formed by plate tectonic activity, specifically continental
collision." (From - Andrew Alden, 'Arm-wavers of the centuries
- landforms and features', http://geology.about.com/od/structureslandforms/a/mountainproblem.htm
|
|
Understanding plate motions [This Dynamic Earth, USGS] "..The Himalayan mountain range dramatically demonstrates one of the most visible and spectacular consequences of plate tectonics. When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways. The collision of India into Asia 50 million years ago caused the Eurasian Plate to crumple up and override the Indian Plate." http://pubs.usgs.gov/gip/dynamic/understanding.html "..Sometimes, when there
is a convergent boundary between two continental plates, subduction cannot
occur. Since continental crust is more bouyant, or less dense, than oceanic
crust, one plate does not easily override the other. Instead, the plates
crumple as they plow into one another, and a very high mountain range
is created. This is a special type of convergent boundary called a collisional
boundary. The Himalayas in India are the result of two continental plates
(the Indo-Australian and Eurasian plates) colliding head on."
"Where plates serving landmasses
collide, the crust crumples and buckles into mountain ranges. India
and Asia crashed about 55 million years ago, slowly giving rise to the
Himalaya, the highest mountain system on Earth. As the mash-up continues,
the mountains get higher. Mount Everest, the highest point on Earth, may
be a tiny bit taller tomorrow than it is today."
"...When two land masses
meet, on the other hand, neither will slide under the other. Instead, the
two crush together at what is known as a collisional boundary. They
crumple and fold. Some pieces of land are thrust over or under other
pieces. The result is a mountain range."
"When an ocean closes and
one continent meets another continent along a convergent margin, they
collide and crumple up, forming huge mountain ranges like the Himalayas;
this is called a collision zone (Fig. 4.14D)."
"...Fold mountains are formed
when two plates move together (a compressional plate margin). This can
be where two continental plates move towards each other or a continental
and an oceanic plate. The movement of the two plates forces sedimentary
rocks upwards into a series of folds. Fold mountains are usually formed
from sedimentary rocks and are usually found along the edges continents.
This is because the thickest deposits of sedimentary rock generally accumulate
along the edges of continents. When plates and the continents riding on
them collide, the accumulated layers of rock crumple and fold like a
tablecloth that is pushed across a table. "
"...Fold mountains are formed
from the collision of continental tectonic plates. Since neither plate
subducts under the other, the colliding plates wrinkle and fold like
a rug being pushed into a wall."
"...While new ocean crust
is constantly being created at mid-ocean ridges, old crust must either
be destroyed or reduced simultaneously. Otherwise the planet would be continually
expanding and increasing in volume. The plates, therefore, emerging along
mid-ocean ridges, sliding over the athenosphere, and grinding past other
plates along transform faults, are almost all headed on a collision course.
When two continents carried on opposing plates ram into each other,
they crumple and fold under the enormous pressure, creating great mountain
ranges."
"..Fold moutains are actually
formed by crust which have been uplifted and folded by compressional forces.
This occurs along convergent plate boundaries where 2 plates move towards
each other, between continental plates or between an oceanic and a continental
plate. The crust and the
rocks get bent and crumpled, and massive layers
of Earth's crust gets uplifted as a result, forming spectacular fold mountains.
"...Where two continental
plates collide, the effect is for the plates to crumple and compress,
creating extensive mountain ranges, such as is occurring at the Indian
and Eurasian plate-boundary with the Himalaya."
"...So when two continents
come together (or collide) they tend to crumple up, generating mountains.
Arabia is currently converging with Eurasia, generating mountain ranges
(e.g. the Zagros of southern Iran)."
"..The mountain belts are
typically formed due to plate tectonic activity. When the plates collide
they crumple and stick together or are sutured together. The process
that produces the mountain building is called orogenesis, which include;
Folding (anticlines ? synclines), thrust faulting, metamorphism, and igneous
activity. The Appalachian, Andes, Apls, Ural, Himalya, Rocky, and Cascade
Mountains are great examples of the mountain belt formation."
"...If the plates collide
and neither plate can subduct under the other,
the crust material will
just "crumple," pushing up mountains. This process does not produce
volcanoes. This kind of boundary can develop later into a subduction zone."
"...When two continents carried
on converging plates ram into each other,
they crumple and fold under
the enormous pressure, creating great mountain ranges. The highest
mountain range in the world, the snow-capped Himalayas, is an example of
a continent-to-continent collision. This immense mountain range began to
form when two large landmasses, India and Eurasia, driven by tectonic plate
movement, collided. Because both landmasses have about the same rock density,
one plate could not be subducted under the other. The pressure of the colliding
plates could only be relieved by thrusting skyward. The folding, bending,
and twisting of the the collision zone formed the jagged Himalayan peaks.
This string of towering peaks is still being thrust up as India, embedded
in the Indo-Australian Plate, continues to crunch relentlessly into Tibet,
on the southern edge of the Eurasian Plate."
"...In the period 1908-12,
theories of continental drift were proposed by the German geologist and
meteorologist Alfred Lothar Wegener and others, who recognized that continental
plates rupture, drift apart, and eventually collide with each other. Such
collisions crumple geosynclinal sediments, thus creating future mountain
belts."
"..Fold Mountain: Again,
the name tells a lot. As one would take an article of clothing and fold
it, so has the earth taken pieces of itself, and through time has, with
great force, pushed pieces of earth upward and folded them over onto themselves.
Example of Fold Mountains includes the Appalachian Mountains."
"..Optional - One of the
questions that might be asked is if the continents are now moving apart,
could they also have moved together. The answer is yes. This phenomenon
is called continental collision. Colliding continents are similar to colliding
cars. If two cars run into each other, they crumple where they meet. The
same thing happens with continents; the crumples are called mountains.
If your students are advanced enough, when you are locating and naming
the continents, have them mark in the Alps, Himalayan Mountains and the
Ural Mountains, or use figure 3 as your base map."
|
There isn't much can be added to this mythological inanity beyond observing the tremendous memic appeal enjoyed by kindergarten 'rumplecrust tectonics' when it comes to so-called 'building' of mountains, and to argue its manifest error when it comes to the global-scale reality of the Earth. Mountains are erosional, and develop from the plateau surface that predates them (to*platstrat)and which to some degree is usually still in evidence. They are not upthrust by any folding. Those folds predate the erosion surface, and form (usually) fairly deep in the Earth's crust by subsidence. Mountains develop from erosion of plateaus, not from the folding that may be exposed in/ on them. Given the views from space (which incidentally postdate the urban myth, but were already known by travellers more than a hundred years ago) what could be more obvious? Mountain 'building' is a destructive process, not a constructive one.Even in Plate Tectonics, the principle driving forces are regarded as vertical - up at spreading ridges, down at subduction zones - with both of them associated with the biggest 'up-structure' on the planet - namely the mantle breaking through the continental crust. Why transmute this vertical driving force of an extruding mantle bubble into a horizontal force, when it already (as vertical) has the capacity to form what we see - gravitational collapse? The true growth of ocean floors towards the ridge is clear from the structural relations at the ridges, meaning that the mantle adjacent to the continental margins is inactive, fossilized, defunct. Transform faults tell us the spreading ridges and subduction zones were once juxtaposed. The oceanic crust is not going down the subduction zone. It is the continental lithosphere that is overriding the oceanic crust (/lithosphere). As in fact Plate Tectonics advertises. Plate Tectonics readily uses this terminology and the process-dynamic overriding to describe the tectonics of continental margins, but deliberately maintains the myth of the mantle being driven under the continents, and disingenuously represents the two as the same, which they are not.
It is the effect of gravitational correction of the continental lithosphere to the enlarging surface of the Earth we are seeing, the adjustment of the early Pangaean Earth curvature to a lessening curvature, and the sliding of the lithosphere out over the mantle, that is the cause of the Fiery Ring of the Pacific, ..not any 'subduction' shoved from half a world away. It is all happening, ..right there, .. in place, .. by gravity, ..gravitational correction of the continental lithosphere on an expanding Earth.
Folding reflects crustal collapse, often in the highest metamorphic regimes of the crust, i.e., deep down, and SINKING .. not high up, tossed on mountains tops, and rising. Once stratigraphic sequence emerges from the sea floor it gets rubbed down - Flat. It's done all its folding before it even gets dry, much less uplifted to the highest reaches of the planet.
Mountains don't get 'built' deep down in the crust. They get formed by erosion once the water recedes, and the higher they get, the more erosion makes them pointy and steep (like mountains).
The really big question here is why such a nonsensical myth as "fold mountains" gets perpetuated.
..Or have your say..