science 2

• Crust (around 5-25m thick)– Earth's solid, thinnest, outermost layer

            – relatively cold, is rocky and brittle; can fracture during earthquakes

            – consists of plates that are either continental or oceanic.
• Continental Plate (30-50 km thick) – contains the different landforms and continents.
• Oceanic Plate (about 8-10 km thick) – heavier, denser, and darker than the continental crust

                                                         – consists the landforms below the oceans and seas.
• Endogenic Forces – are those that come from within the Earth.

                                  – force produced by convection current in the mantle
• Exogenic forces – are those that develop outside the surface of Earth.

                             – force of the wind
• Mantle (1800m thick) – made up of magma and is divided into the upper mantle, 

                                        asthenosphere, and lower mantle

                                    – is so massive, it makes up a total of 84% of Earth’s volume
• Magma – part of the asthenosphere which is extremely hot, dense, rock; flows like asphalt
• Upper Mantle (1600°F) – made of solid bedrock that contains most of Earth's mass.

                          – lower lithosphere and the asthenosphere are both part of the upper mantle.
• Lithosphere – made up of granite and basalt by the crust and upper mantle which is rigid, hard; 

                          makes up the tectonic land plates about 100 km thick.
• Asthenosphere – soft layer made up of granite and basalt, beneath the lithosphere which’s 

                                 temperature and pressure are so high that rocks melt.
• Core – innermost layer of the Earth which consists of the outer core and the inner core.
• Outer core (1400m thick)– is located about 1800 miles below the Earth’s surface; made up of molten iron and nickel with about 10 percent sulfur; has temperatures between 4000 and 9000 degrees
• Inner core – is made up of solid iron and nickel; under extreme pressure that is why it remains solid 
• Alfred Wegener – German geologist and meteorologist who first proposed the continental drift theory.

                             – also proposed that the relative positions of the continents are rigidly fixed because 

                                they are slowly moving at a rate of almost 1 meter (0.91m) per century
• Pangaea – one giant supercontinent , meaning all lands, which was surrounded by a single ocean called Panthalassa. Pangaea, over time had separated and drifted apart
• Continental Drift Theory – states that there was a supercontinent called Pangaea.

                                            – further claims that the continents consist of lighter rocks that rest on top 

                                               of heavier crustal materials.

                                            – this theory was initially rejected by some scientists but decades later, it 

                                               became the forerunner of the plate tectonics theory.
• Theory of Plate Tectonics – tells that the surface of Earth is divided into several pieces of plates that 

                                                 "float" along the asthenosphere.

                                              – explains how the different geological phenomena like earthquake, 

                                                 volcanism, continental drift, and mountain formation occur.
• Tectonic Plates – plates move along their boundaries in different directions and at different speeds.
• Earth’s interior is very hot; release of heat from the core produces convection current in the mantle.
• Convection Current – causes the oceanic and continental plates to move.
• Convergent Plate Boundary – formed when plates meet from opposite directions causing one 

                                                       plate to be subducted or moved beneath the other.
• Two oceanic plates collide with one another, one may be pushed under the other. 
• On the other hand, when an oceanic plate collides with a continental plate, the oceanic plate is subducted beneath the continental plate; forms a huge mountain or a deep oceanic trench.
• Divergent Plate Boundary – formed when two tectonic plates move away from each other. 
• Rift – the sunken blocks form a valley
• Seafloor Spreading 

  When two ocean plates move apart, magma rises from the mantle to fill the gap. When magma cools, a new seafloor is formed.
• Transform / Sliding Boundary Plate – zone between two plates sliding horizontally past one 

                                                                  another 

                                                               – causes friction and a strong jerky motion of the plates as they 

                                                                 move apart, which produces an earthquake.
• Earthquake – is the shaking or tremblingof Earth's crust 

                      – may be caused by volcanic eruptions, sudden displacement of Earth's crust along a 

          fault, or collision of plates in the deep changing its surface zones of Earth.
• Intensity of Shaking – depends on the amount of energy released. This may range from a minor jolt 

  to a violent tremor.
• Focus / Hypocenter – the point where the sudden rupture of the rocks or plates takes place
• Epicenter – the point on Earth's surface directly above the focus.
• Circum-Pacific Belt or Ring of Fire – is the world's largest earthquake belt where it is located 

  around the coast of the Pacific Ocean and Alaska to Kurile, Japan, Mariana, and the Philippine trenches.

          – where 90 percent of the world’s earthquakes and 80 percent of the world’s largest earthquakes occur.
• Seismologists – are scientists who study earthquakes and their effects.
• Seismograph – where you can gather data and monitor Earth's crust.

            – instrument used to record the intensity, direction, and duration of the movement of the 

  ground.
• Seismogram – record of an Earth tremor produced by the seismograph; indicates the magnitude of 

  energy released during an earthquake.
• Intensity – gives a qualitative description of the severity of shaking. 

                  – is determined from the effects on people, infrastructures, and the natural environment. 
• Modified Mercalli Intensity Scale – the descriptive scale which the intensity uses.
• Magnitude – indicates the quantitative measure of the size of the earthquake at its source.

                     – represents the amount of energy released by an earthquake.
• Richter Magnitude Scale – scale used to measure the earthquake's magnitude.
• 0-2 – Generally not felt but record