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Earth Science: Geological Forces that Gives Life to Earth
There are six forces that give life and shape the earth, these are: diastrophism, earthquakes, mountains, plateaus, plains and volcanism.
Diastrophism - This is the dynamic internal forces. It tends to elevate the earth’s surface.
Types of earth movement
- Uplift- this is a movement of the earth in which the crust rises.
- Subsidence- this is a sinking or setting a part of the earth’s crust.
- Thrust-this is the horizontal movement of the crust.
Theories of Diastrophism
There are three theories, these are:
1. Theory of Isostasy
- Form a Greek word means “equal standing”. As the rock is removed due to erosion from the higher region and deposited to a lower region as the result the lower region gradually becomes heavier and slowly sinks, while the higher region slowly rises.
2. Contraction theory
- This means that the earth is gradually shrinking. It emphasizes that the stronger and heavier blocks of the crust is sinking in and then the weaker strata are squeezed upward
- This is where the continents have been move above over the earth’s surface.
3. Expansion theory
- This is where the earth is gradually spreading. This can change the position of the continent.
Features of Earth Movement
- Deformation of rocks - This is the effects of diastrophism usually happen in the deformation of rocks.
- Folds - This is a bend or flexure in a rock like of the waves of the ocean. There’s a crust or uphold and a trough or downfall. Anticline is the crust of the rock which is in the higher region and the trough of the rock is the syncline which is in the lower region.
- Dip and Strike - Dip is the angle between horizontal plane and a surface. Strike is a direction of a line where it meets the horizontal plane.
- Pitching fold - This is where the land is in slant downward.
- Joints and Fissures - This is where it has a gap or fracture between the rock walls.
- Faulting - A body or rock wherein it has been broken and displaced.
Types of Faults
- Thrust fault- this is characterized by a horizontal displacement wherein the hanging wall is moved upward in relation to the footwall.
- Normal Fault- this is characterized by a vertical displacemet wherein the hanging all is moved downward.
- Reverse fault- this is the opposite of the normal fault in which the fault plane moves upward.
What are the effects of Earthquakes in your locality?
This is a ground displacement associated with the sudden release in the form of seismic waves and of built-up stress in the lithosphere.
- Seismograph- is a sensitive earthquake recording instrument.
- Seismologists- are the scientists who study earthquake.
Three major seismic waves
- Primary waves- it moves forward and backward direction.
- Shear wave or secondary wave- it oscillates back and forth at right angles. This can cause strong movement that can record by seismographs.
- Surface waves- this travels along the outer layer of the earth. This has two kinds: R or Rayligh wave and L or Love waves. This is the last wave to arrive.
Causes of Earthquakes
1. Crustal plates
- Subduction- is the reverse of seafloor spreading. This is where on slide to another plate causing to create earthquakes.
2. Man-made quakes
- Tremors- this means that it is an artificial construction of a dam that induced quakes.
- Seismic waves - It is a sound traveling across the earth caused by earthquake.
How does Earthquake Occur?
Effects of Earthquakes
- Soil reactions
How to prevent Earthquake
- Statistical data- earlier recorded quakes use for future probabilities.
- Seismic gaps- this is the distance of the location of the quakes to the other nearer places.
- Earthquake precursors
Difference between Intensity and Magnitude in Earthquake
- Intensity- it is a measure of the damaging effects of an earthquake at a particular spot or within a given area.
- Magnitude- it is a measure of earthquake size and it is a measure of intensity of ground shaking.
How Mountains are Made
- Types of Weathering and Causes of Soil Erosion
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- Types of Rocks: It’s Cycles and Classifications
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This is a high and less rugged form wherein rocks are intensely deformed by horizontal stresses.
Orogenesis- the process of mountain building that involves:
- Rock sequences
- Structural deformation
- Igneous activity
Classification of mountains
- Geographically arrange
- Structurally arrange
Kinds of Mountains
- Volcanic mountains- this is a result of volcanic events. Examples are Mounts Apo, Mayon, Taal, Vesuvius, Mt. Etna and Mt. Fuji.
- Folded or Complex Mountains- they are structurally arranged. Examples of this are Alph, Urals, Himalayas, and Appalachian mountains.
- Erosion volcanic mountains- this is a single or group of mountains caused by erosion of stream. Examples are The Sierra Madre Mountain, The Tagaytay Ridge, and Cordillera Mountains.
- Fault-block mountains- this formed by displacement of rock along a fault. Example is the Marinduques Mountains.
- Up warped mountains- this formed cause of the vertical displacement along high angle faults. Examples are Black Hills in Western South Dakota and the Adirondack Mountains in New York.
Economic values of mountains
- The humid slopes provide lush grasses for grazing
- The streams provide water for irrigation and electric power.
- Contain minerals and metals
- Sources of stones and woods for building
- Provide comfortable vacation
- Places for relaxation and recreation
It is an extensive upland region. It elevation exceeds 2,000 ft. There’s a difference plain and plateaus. Plateaus have high relief while plain has low relief. This may be caused by diastrophism and volcanism.
Economic importance of plateaus
- They can be dammed to impound water
- The stored water can be used for irrigation
- Reveal ore deposits
- Crops in the upper parts can be grown because of low temperature.
- Used for pasture lands
Mountain and Plains
- Young plateau- rounded surfaces and gentler slopes and has few streams
- Mature plateau- these are called mountains and have numerous streams
- Old-age plateau- is a steep-walled with flat surfaces.
It is a land surface that is flat and relatively close to sea level. This is usually portions of nearly level sea bottom.
Kinds of plains
- Coastal or Marine plains- formed when sea are uplifted
- Central plain- has flat interior plains
- Flood plains- this is smooth nearly level surfaces away from the river.
- Delta plains- formed at the mouths of the rivers.
- Glacial plains
- Piedmont plains
- Alluvial plains
- Lake plains
This covers all kinds of volcanic events.
- Volcano- is a vent, hill or mountain from which hot rock materials are ejected. It formed when tectonic plates and oceanic trenches converged and collided wherein they slid past each other.
- Magma- from a Greek word means “kneaded mixture” a dough or paste. It is any hot mobile material within the earth.
Active and Inactive Volcano
- Active volcano- this is a volcano with a record of eruption within recent history.
- Inactive Volcano- this is a volcano that has never erupted within historic times.
Types of Volcanic cones
- Cinder cone- a steep-sided volcanic made up mostly of ashes.
- Shield volcano- a low flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava.
- Composite cones- form when viscous lavas of andesitic composition are extruded.
Types of Volcanic Eruptions
- Quit –this is oozing or quite type during eruption.
- Explosive- explodes with unbelievable violence.
- Intermediate- sometimes quite and sometimes explosive.
- Fissure- large amount of volcanic materials are extruded.
Products of eruption
- Gases and vapors
- Pyroclastic materials
- Ammonia is used for making fertilizer
- Methane use for fuel gas
- Lava, volcanic ash and dust use to fertile soil
- Pyroclastic materials need for glass making and pottery or porcelain production
- Provides geothermal steam for power generation