Internal energy and landforms

Internal energy and landforms

1. types of plate boundaries

   • divergent or constructive boundaries
     • 1. zone where two plates move apart 2. create new lithosphere 3. rifts and ridges are created too 4. Seismic and volcanic activity 5. Tension forces
       • 5. African rift
       • 6. Mid-Atlantic ocean ridge
   • Transform or passive boundaries
     • 1. make a lateral movement displacement 2. lithosphere is neither created or destroyed 3. lot of seismic activy 4. transform faults are created 5. shear stress
       • 5. San Andreas fault
       • 6. Strait of Gibraltar
   • Convergent or destructive boundaries
     • plates collide and, lithosphere is destroyed. There are 3 different types:
       • oceanic-oceanic landfrom: 1. seismic and volcanic activity, 2. island arcs and trenches are created. 3. Some examples include Japan and the Philippines 4. compression forces
         • island arc: 1 active volcanoes 2. all islands from the same age 3 erupt viscous magma and have violent explosions 4. ex: Japan and Philippines
         • volcanic archipielagos: 1. found in middle of an ocean plate 2. only the island above the hot spot is active 3. their age increase 4. erupt fluid magma and not violent explosions 5. ex: Hawaii
       • oceanic-continental landform: 1. Seismic and volcanic activity 2. trenches and mountain ranges are created 3. Some examples include the Andes(non collisional orogenes) 4. compression forces
       • continental-continental landfrom: 1. seismic but NO volcanic activity 2. mountain ranges are created(collisional orogenes) 3. some examples include Alps, Himalayas and pyrenees 4. compression forces
   • edges or boundaries between plates that are very active geological areas

2. Plastic deformation: FOLDS

   • Fold: created when rocks defrom, because of compressional stress. Rocks do not brerak but the fold
     • based on the relative age of the material
       • 1. Anticline: the core has the oldest materials
       • 2. syncline: the core has the youngest materials
     • based on the positionof the axial plane
       • 1. Upright: axial plane has an angle of elevation of 90º or close to
       • 2. Inclined: axial plane has an angle of elevation between 85º and 10º
       • 3. Recumbent: axial plane has an angle of elevation of less than 10º
     • based on the degree of symmetry
       • 1. Symmetrical: the axial plane divides the fold in 2 symmetrical or nearly halves
       • 2. Assymetrical: the axial plane divides the fold into 2 assymetrical halves

3. Brittle deformation: FAULTS

   • fault: fractures in the rocks on the Earth's surface where the blocks have been displaced (usually cause earthquakes)
     • 1. Normal fault: occurs when the fault plane is inclined to the hanging wall (tension forces)
     • 2. Reverse fault: occurs when the fault plain in inclined to the foot wall(compression forces)
     • 3. Transform fault: the movement of the blocks is horizontal, NO hanging or foot wall(shearing forces)
     • 4. Hosts and grabens: series of normal faults are present. 1.1 Horsts are the blocks at higher elevation 1.2 Grabens are the blocks at lower elevations. (in continental rifts)

4. magmatism and metamorphism

   • Earth is geologically active planet because of the heat inside it(geothermal gradient: +depth, + temp
     • 1. Magmatism rocks should be molten but, due to pressure, they don´t melt.
       • 3. Subduction zones: rocks melt due to a rise in temperature and the presence of liquids
       • 2. Hot spots: rocks melt due to a drop in preassure
       • 1. Ocean ridges and continental rifts: rocks melt due to a drop in preassure
     • 2. Metamorphism: occur when the temperature increases and pressure produce transformations in rocks
       • 1. Contact or thermal metamorphism: increase in temperature
       • 2. regional metamorphism: increase in temperature and preassure
       • 3. dynamic metamorphism: increase in pressure

5. external geological process: make the relief smoother by removing materials from hight to low altitude

   • relief: the height of the landforms on the Easth`s surface. It is the difference between maximum and minimum elevations within a given area(ex: mountains, oceans, continents...)
     • 1. Weathering: alters and breacks up rocks
     • 2. Erosion: geological agents erode land due to their own force and they break into small pieces the materials they transport
     • 3. Transportation: materials produced from erosion are transported to depressed zones on the Earth's surface
     • 4. Sedimentation: materials deposited that agents transpport. It creates different landforms

6. orogenies: geological periods in the past during which mountain ranges were formed

   • orogens:a belt of the earth's crust involved in the formation of mountains
     • 1. non-Collisional orogens: 1. formed by continental-oceanic landforms 2. have seismic and volcanic act. 3. trenches are created 4. some examples include the Andes
     • 2. Collisional orogens: 1. formed by continental-continental landforms 2. only have seismic activity, NO volcanic 3. no trenches are created 4. some examples include the Alps and Himalaya

7. The wylson cycle

   • Wilson suggested that in the Earth there have been 2 proceesses of RIFTING and REUNITING
     • 2. Continental rift stage: fractures appear and make the lithosphere thinner and lead to the formation of a continental rift
     • 3. Narrow sea stage: the continent is now separated and , new oceanic lithosphere and a ridge begin to form between the 2 slides
     • 4. Maturing ocean stage: the division continues and sea-floor spreading increases the formation od oceanic lithosphere(ex:atlantic ocean)
     • 5. Shrinking ocean stage: ocean begins to close because of d¡subduction on its boundaries(ex: Pacific ocean)
     • 6. Convergence theory: The ocean is almost closed. The continents converge with marine sediments on their edges
     • 8. Final stage: continental masses are joined together and a mountain range is formed from the collison of the continents(plate boundary will become inactive)
     • 7. Continental collision stage: boundaries of both continents and the sediment trapped between them are deformed
     • 1. A dome forms: the heat under the continent causes tge crust to expand and lift up

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