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types, causes and effects of crustal movements
Transcript of types, causes and effects of crustal movements
-it is the dynamic internal forces that generally tend to elevate the earth's surface. They are in constant battle against external forces that tend to wear away the land surface.
TYPES/CAUSE OF EARTH MOVEMENTS
-it is the movement of the earth where in the crust rises.
-it is the sinking or setting of a part of the earth's crust with respect to the surrounding parts.
-it is the horizontal movement of the earth's crust.
EFFECTS OF EARTH'S MOVEMENTS
1. THEORY OF ISOSTACY
-isostacy came from the greek word meaning 'equal standing".
-this theory states that as the rocks from higher region are removed be erosion and deposit on a lower region, the higher region slowly rises while the lower region becomes heavier and slowly sinks.
2. CONSTRUCTION THEORY
-it states that the earth is gradually shrinking. as the shrinking occurs, the stronger and heavier blocks of the crust sink while the weaker strata are crowded and squeezed upward.
3. CONVECTION THEORY
-it is the theory which would account from the pushing ang colding of rocks through convection current. This process is true when it occurs under a continental mass.
4. CONTINENTAL DRIFT THEORY
-it is the theory which accounts for diastrophic movement a d for the folding and faulting along the edges of the continents.
5. EXPANSION THEORY
-it is the theory which states that the earth is gradually expanding. Expansion of the earth would change the position of the continents.
-mountains are lands that rise high above the surrounding land.
FORMATION OF MOUNTAINS
-are the most common type of montains that are made from rock layers that where squeezed from opposite sides causing the rock layers to fold.
-a fault is a huge crack in the rocks. The grand teton mountains (wyoming) and the sierra nevada mountains (california) are examples of fault-block mountains.
-are formed by wind or water nearing down weak spots in land and carrying it away. (example rocky mount in western US).
-can be standing alone or be a part of one big chain of volcanoes are ring of fire.
Volcanism is a part of the process by which a planet cools off. Hot magma, rising from below, reaches the earth, eventually, but not always, erupts onto the surface in the form of lava.
Rising magma gathers in a reservoir in a weak portion of the overlying rock is called the magma chamber.
The different reasons why a volcano is formed are:
>via plumes or hot spots in the lithosphere
>as a result of subduction of the nearby lithosphere.
DIFFERENT KINDS OF VOLCANOES
-are simple volcanoes which a bowl-shaped crater at the summit and only grow to about a thousand feet, the size of a hill.
-another well known cinder cone is in the middle of CRATER LAKE.
-famous cinder cones include PARICUTIN in Mexico
-are the most majesty and also known as strato- volcanoes.
-famous composite volcanoes include mount Fuji in japan, mount Cotopaxi in Ecuador, Mount Shasta and Lassen in California, Mount hood in Oregon, Mount St. Helens and Mount Rainier in Rashington, Mt. Pinatubo in the Philippines and Mt. Etna in Italy.
-can grow to be very big. In fact, the oldest continental region of earth may be the remains of ancient shield volcanoes.
LOCATION OF VOLCANOES
Volcanoes are mainly found along those plate boundaries:
1. where an oceanic plate and continental plate boundaries.
2. where two oceanic plates meet
3. where plates move apart
TYPES OF VOLCANIC ERUPTIONS
-it is non-explosive but sends fountains of lava hundreds of feet into the air in spectacular scarlet tongues.
-the eruption is often proceeded by loud rumblings and earthquakes.
-between the quiet and the explosive kinds is the intermediate which is sometimes quiet, sometimes explosive or a combination of both.
-the largest amount of volcanic materials are extruded from cracks in the crust called fissures.
DISTRIBUTION OF VOLCANOES
Almost all of the volcanoes of the world are found into two major belts which cover match of the same regions as the earthquakes belts.
They are roughly the zones of fracture in the crust. These two belts are:
>Circum-pacific belt also called ring of fire