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Earths Crust Convection currents Continental drift – idea that continents have moved slowly to their current positions due to convection currents in.

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Presentation on theme: "Earths Crust Convection currents Continental drift – idea that continents have moved slowly to their current positions due to convection currents in."— Presentation transcript:

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2 Earths Crust

3 Convection currents

4 Continental drift – idea that continents have moved slowly to their current positions due to convection currents in the mantel. Pangea – the idea that the all land masses on earth were once a single large land mass.

5 Ocean floor spreading – theory that hot less dense material below Earths crust rises toward the surface at the mid-ocean ridges. Then, it flows sideways, carrying the seafloor away from the ridge in both directions. http://geology.com/nsta/divergent-boundary-oceanic.gif http://geology.com/nsta/divergent-boundary-oceanic.gif Convection current – unequal distribution of heat in the mantel causes a net movement in a circular motion.

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7 The Earths CRUST is the outer most part of the Earths surface. Average 32 km thick Thickest point 70 km (in mountains) Thinnest point 8 km (under ocean)

8 Plate tectonic – theory that Earths crust and part of the upper mantle are broken into sections called plates. Lithosphere – all of the earths crust and part of the upper mantle. http://www.allaboutspace.com/subjects/astronom y/planets/earth/Inside.shtml Asthenosphere – plastic like layer below the lithosphere. The ridged plates of the lithosphere float on the more plastic layer called the asthenosphere.

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11 Deformation – The breaking, tilting, and folding of crustal rock due to crustal movement. (three types of forces) 1.Compression – squeezing of earths crust that compacts the rock. Convergent boundary 2. Tension – is the pulling apart of the earths crust. Divergent boundary. 3. Shearing – pushes rocks side by side in opposite directions. Transform boundary.

12 Convergent boundary Divergent boundary Transformation boundary

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14 subduction Rift valley

15 FAULTS Normal Fault – fault caused by tension stress that moves the hanging wall down relative to the foot wall.

16 Reverse Fault – fault caused by compression forces where the hanging wall will move up relative to the foot wall.

17 In Lateral (strike-slip) faulting, the two blocks move either to the left or to the right relative to one another. Strike-slip faults are associated with crustal shear.

18 Thrust Fault – is formed when compression causes the hanging wall to slide over the foot wall. (almost horizontal movement)

19 Facts about folds/faults. 1.increased temp. =s fold 2.decreased temp =s fault 3.increased pressure =s fold 4.decreased pressure =s fault 5.rock type – brittle =s fault 6.rock type – ductile =s fold 7.time – greater the time =s fold 8.time – less time =s fault

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24 Fault block mountain is a mountain created by blocks of rock uplifted by normal faults.

25 Rift Valley are valleys created when a block of land between two normal faults slide downward.

26 End of chapter 10

27 Folds – are bends in rocks without breaking folds have two parts 1.Anticline – upward part of fold 2.syncline – downward part of fold Anticline

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29 Plateau – is a large area of flat land that is raised high above sea level. Usually bordered by cliffs or mountains.

30 Domes – is the uprising area caused by magma

31 Floating crust - more dense less dense

32 A balance exist between the downward force of the crust and the upward force of the mantle called ISOSTASY.


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