PPllaattee TTeeccttoonniiccss aanndd tthhee EEaarrtthh’’ss IInntteerriioorr Chapter 5 ’’s Internal Structure 

 Core Crust  Thin – basins . ~ 3 miles

ranges . ~ 30 miles

 Deepest hole drilled – About 7 miles . Russia Crust  Constitutes less than 1% of Earth’’s total mass

 Average – 2.8 g/cm3

Crust  Crust ―floats‖ on mantle

stand higher – thick and less dense

– thin and more dense

Oceanic Crust vs  Continental crust made of – rocks containing and aluminum – e.g.,  Oceanic crust made of – rocks containing silicon and – e.g., Mohorovicic Discontinuity  Boundary between the crust and the mantle – 1 to 2 km thick – seismic P-waves increase in velocity Mantle  1800 miles thick

 Density – 4.5 g/cm3

 80% Earth’’s volume Mantle  Mostly solid

 Denser silicates rich in Mg and Fe – (Gk. stone shell)  ~ 100 miles thick

 Crust + Upper mantle (Gk. weak shell)  Part of upper mantle

 Plastic layer – Completely liquid in places ()  18-60 miles thick Mesosphere (Gk. middle shell)  Solid dense mantle below asthenosphere

Core  ~ 2000 miles thick

 Density – 11.0 g/cm3

 Half the radius and one-third mass of Earth

Outer Core  Liquid

 molten iron, nickel, cobalt, sulfur, or silicon

 origin of Earth’’s magnetic

Inner Core  Solid (near melting point or partly molten)

 Iron

 8000° F

 3 million atm PPllaattee TTeeccttoonniiccss Have the contiinents drifted? Have the continents drifted?  Antonio Snider (1859) proposed the continents drifted – Creationist – Based his idea on Genesis 1:9-10 Genesis 1:9-10  9 And God said, Let the waters under the heaven be gathered together unto one place, and let the dry appear: and it was so  10 And God called the dry land Earth; and the gathering together of the waters called he : and God saw that it was good.

Evidence?  The fit of the continents (taking into account the continental shelves).  Correlation of types across ocean basins.  A -striped pattern of magnetic reversals parallel to mid-ocean floor , in the volcanic formed along the rifts, implying along the rifts.  Seismic observations interpreted as slabs of former ocean floor now located inside the earth.  Positional shifting of continents

 Alfred L. Wegner – German (1880-1930)

– ―all ‖ –

Pangaea Plate Tectonic  The earth''s surface (lithosphere) consists of rigid plates, each moving relative to adjacent plates. Deformation occurs at the edges of the plates by three types of horizontal : – Divergence – plates moving apart – Convergence – plates compressing together or one sliding under the other () – Transform –plates sliding past each other along a line Earth’’s plates Theory of Plate  Movement of plates explains:

– volcanoes Divergent Boundaries  Occurs as the floor pulls apart at rifts or splits – Mid-Atlantic Ridge Convergent Boundaries  Occurs when one plate slides under another (subduction) or two plates collide together – beneath beneath – Indian- colliding with

Three Types of Convergent Boundaries  Ocean-ocean – two oceanic plates converge with one subducting under the other – Associated with arcs (Aleutian )

 Ocean- – oceanic pllate and continental plate collide with oceanic plate subducting under continental plate – trenches and volcanic mountain chains (Sierra Nevada )

 Continent-continent – two continental plates collide and ―buckle‖ – No subduction – Upfolded ( and Himalayan Mountains) Transform Boundaries  Occurs where one plate slides horizontally past another – (Pacific Plate slide against ) Mid-Atlantic Ridge  20,000 feet below surface  ~38,000 miles of ridges around globe (oceanic ridge)  divides into two equal parts  At , forms Iceland

Mid-Atlantic Ridge  (trough) in middle of crest – 20 miles wide

earthquakes under crest

 Heat escaping rift Iceland  ground cracks in Iceland are widening, often accompanied by volcanic activity – Between 1975 and 1984 there was a 23 feet separation Mid-Atlantic Ridge

Satellite imagery Interpretation of Observations of Mid-Atlantic Ridge  Magma rises up at the rift forming new oceaniic crust – ―Younger‖ crust is at ridge and ―older‖ crust away from ridge  Rocks acquire magnetism as they cool – Records earth’’s direction at – Continuous seafloor spreading should have a smooth magnetic ―tape recording‖ of reversals

Zebra stripe pattern Problems for ―Slow and Gradual ‖  Zebra stripe pattern has been confirmed – Drilling in the basalt shows magnetic polarity changes in patches down the holes with no consistent pattern with depth. . Indicates rapid formation of basalt—not slow and gradual formation  Magnetic reversals in lava have been shown to occur rapidly

 Mid-Atlantic Ridge spreads about 2 inches per year

IIss tthhee pprreesseenntt rreeaallllyy tthhee kkeeyy ttoo tthhee ppaasstt?? Catastrophic Plate Tectonics  Pre-flood supercontinent and dense ocean floor rocks  Cold dense ocean floor sinks into softer, less dense mantle – Edges sink faster due to and drag the rest of the floor with it in conveyor belt fashion

Catastrophic Plate Tectonics  Faster movement creates more friction and heat in the mantle, reducing its resistance, and making the mantle move faster – Runaway subduction

Catastrophic Plate Tectonics  Mantle material is displaced, causing large scale movement through entire mantle – Causes enough throughout earth to break up original single land mass  Hot, mantle material rises up amid cracks and vaporizes some ocean water causing geysers (Gen 7:11; Gen 8:2)  Steam condenses in atmosphere to cause global (Gen 7:11-12) Catastrophic Plate Tectonics  Rapid subduction of the cooler pre-flood ocean floor into the mantle would have resulted in increased circulation of viscous fluid (note: plastic, not molten) rock within the mantle.  accelerated in the core would cause rapid geomagnetiic reversals – these would be erratic and locally patchy, laterally and at depth, just as the data indicate Catastrophic Plate Tectonics  Model provides mechanism for retreat of flood waters (Psalm 104:6-8) – Vertical earth movements at end of flood as opposed to horizontal movements at beginning  Plate collisions would have pushed up mountains – Slow movement would not be forceful enough to push up Himalayans at Indian-Australian and Eurasian plates

Psalm 104:6-8  6 You covered it with the deep as if it were a garment; the waters stood above the mountains. 7 At Your rebuke the waters fled; at the sound of Your thunder they hurried away - 8 mountains rose and valleys sank -to the place You established for them Final Summary  The idea is quite new, and radical, and much work has yet to be done to flesh out the details. There may even be major modifications to the theory that increase its explanatory power, or future discoveries could cause the model to be abandoned. Such is the of scientific progress. Scientific models come and go, "But the word of the Lord endures forever" (1 Peter 1:25). Future Consequences predicted by Plate Tectonic Theory  Portions of California will separate from the rest of  The Italian ―boot‖ will disappear  will link to will separate from the Near East