The Earth’s Fractured Surface PLATE TECTONICS The Earth’s Fractured Surface

PLATE TECTONICS PLATE TECTONICS = the study of the movement of plates and the effects they have on the surface of the earth.

PLATE TECTONICS New discoveries about the earth’s interior in the 1960s: Lithosphere is not one piece, rather it is broken into plates (plate = a slab of lithosphere that has definite boundaries or edges)

Major Plates of the Lithosphere Figure 6.1 pg 87

PLATE TECTONICS The plates are constantly in motion. HOW? The plates are set in motion by the convection currents in the asthenosphere The earth’s heat engine heats the rock and causes it to swirl (rising when heated and sinking when cooled) http://www.youtube.com/watch?v=ryrXAGY1dmE&list=PL6BB621121FEF758A&index=2

PLATE TECTONICS

PLATE TECTONICS How do we know where the plate boundaries are? The boundaries occur along the major earthquake belts of the world These plates are hitting against one another Quakes seldom occur in the interiors of the plates https://www.youtube.com/watch?v=-zNyVPsj8zc&index=5&list=PL6BB621121FEF758A – Earthquake video

Major Plates of the Lithosphere Figure 6.1 pg 87

World Earthquake Epicentres Figure 6.3 pg 88

PLATE BOUNDARIES (Earthquakes) There are 3 main types of plate boundaries (which cause folding, faulting, and vulcanism): CONVERGING – two plates that are moving towards each other. Two types of converging boundaries include: Collision – where two plates containing continents are meeting

Collision Zone Between Two Continental Plates Figure 6.19 pg 104

PLATE BOUNDARIES Subduction – where an oceanic plate is sinking below a plate containing continents http://www.youtube.com/watch?v=KCSJNBMOjJs&list=PL6BB621121FEF758A 30-34

PLATE BOUNDARIES DIVERGING – develop where two plates are moving apart or separating from one another.

PLATE BOUNDARIES TRANSFORM FAULT BOUNDARIES – two plates are slipping and sliding past one another.

Transform San Andreas Fault Figure 6.13 pg 98

Orchard Offset Along San Andreas Fault, California Figure 6.16 pg 101

PLATE TECTONICS Plate movements produce 3 tectonic processes that change the surface of the lithosphere: Folding – bends and twists the rocks due to compression and squeezing from two plates moving together Faulting – rocks move past each other along a crack, plates are sliding past one another, or moving together

PLATE TECTONICS Vulcanism – movement of magma beneath the earth’s surface. Plates are separating or coming together ** All 3 of the above movements combine to create major mountain chains (i.e. the Rockies, the Andes, etc.)

PLATE TECTONICS (Volcanoes) HOT SPOTS = strong upward currents of magma in the upper mantle that “burn a hole” through the plate creating a volcano Hot spots are not always related to the plate boundaries More related to areas where there is lots of magma in the upper mantle

https://www.youtube.com/watch?v=WwBVG0Si7rs – Hawaii Erruption World Hot Spots Figure 6.4 pg 89 http://www.youtube.com/watch?v=4aYQixhdWY4

Rock Types Original molten rock from deep within the earth Igneous Original molten rock from deep within the earth Impervious to water (water cannot soak through it) Two types: Extrustive Cools very fast, created by lava Intrusive Cool very slowly, created by Magma below the earths surface Basalt Granite

Rock Types Sedimentary Sandstone Broken pieces of rock carried away by erosion and deposited in layers and compressed by the weight above Erosion = the gradual wearing away of land or rock by natural forces (i.e. wind, water, etc) Sandstone

Rock Types Metamorphic Marble Rock that has been transformed by intense heat and/or pressure Molecular structure of the rock is slightly altered to give it a different form Marble

Rock Cycle Summary Rocks can be transformed through the rock cycle. Rock can be created from hot, melted magma that rises from the Earth’s crust. It cools and hardens to form igneous rock. This rock may be broken down into particles or sediment. Eventually the sediment hardens to form sedimentary rock. Pressure and heat can cause this rock to melt again forming metamorphic rock. (This may contain valuable resources.) https://www.youtube.com/watch?v=SRaInMDNyE8