continental drift and plate tectonics. alfred wegener 1880-1930 ●german scientist ●introduced...
TRANSCRIPT
Continental Drift Continental Drift and Plate Tectonicsand Plate Tectonics
Alfred WegenerAlfred Wegener1880-19301880-1930
● German scientist● Introduced the Theory of
Continental Drift in his book The Origin of the Continents and Oceans (1915)
● Many scientists had noticed the remarkable fit of the coastlines of South America & Africa ● First to use geological and
paleontological evidence to show these continents were once joined
Evidence of PangaeaEvidence of Pangaea
Theory of Continental DriftTheory of Continental Drift
• Proposed by Wegener in 1915• Used evidence from climate, fossils and
landforms to match up the continents• All of the continents were once joined in one
large supercontinent called Pangaea and have since drifted apart
• Wegener did not have a force to provide the movement so it was not accepted until the 1950’s● Wegener spent much of his life defending his theory
Wegener’s Continental DriftWegener’s Continental Drifthttp://www.ucmp.berkeley.edu/geology/anim1.html
225 million years ago all 225 million years ago all continents connected in continents connected in one land mass called one land mass called
PangaeaPangaea
180-200 million years 180-200 million years ago Pangaea separated ago Pangaea separated
into Laurasia and into Laurasia and GondwanalandGondwanaland
135 million years ago 135 million years ago Laurasia and Laurasia and
Gondwanaland began to Gondwanaland began to separate into continentsseparate into continents
65 million years ago the 65 million years ago the continents move even continents move even
further apartfurther apart
The position of the The position of the continents on Earth continents on Earth
todaytoday
Untold Untold Tragedies of Tragedies of Continental Continental
Drift Drift
The CrustThe Crust
• This is where we live!
• The Earth’s crust is made of:
Continental Crust
- thick (10-70km)- buoyant (less dense than oceanic crust) - mostly old - granite
Oceanic Crust
- thin (~7 km)- dense (sinks under continental crust)- Young - basalt
Earth’s InteriorEarth’s Interior• Lithosphere: Area
of the crust and the upper mantle.– Crust:
• Outer most layer• Continental crust
(less dense granitic)
• Oceanic crust (more dense basaltic)
• Asthenosphere:– Rocks are at or near
melting point– Exhibits plasticity – a
solid that flows like a liquid
AssignmentAssignmentIn your spiral – draw and color a picture of the Earth’s
interior, labeling the following:
Wegener’s Puzzling EvidenceWegener’s Puzzling Evidence1. Label the land masses on each sheet. Color the
fossil areas to match the legend below.
2. Cut out each of the continents along the edge of the continental shelf (the outermost dark line). Alfred Wegener's evidence for continental drift is shown on the cut-outs. Wegener used this evidence to reconstruct the positions of the continents relative to each other in the distant past.
3.Try to logically piece the continents together so that they form a giant supercontinent.
Africa
S. America
Australia
India
Antarctica
Plate TectonicsPlate Tectonics• Proposed in 1960’s by a variety of scientists
including Hess, Dietz and Vine• Suggests that the lithosphere is broken up into
many plates which are moving around the earth in different directions
• All of the continents were once together in one supercontinent – Pangaea
• Movement is caused by convection currents in the mantle of the Earth
• Explained the cause of earthquakes, volcanoes, mountain building
Plate TectonicsPlate Tectonics
• Plate Tectonics: Theory that the Earth’s lithosphere is broken into plates and float on the asthenosphere
• Convection Currents: Drives plate motion – hot magma rises from core, cools and sinks back to core – cycle starts over (think of a lava lamp)
Double BubbleDouble Bubble
• Make a double bubble map of Continental Drift and Plate Tectonics
CONCLUSIONCONCLUSION
• Imagine you are Alfred Wegener in 1915. Write a Claim – Evidence – Reasoning about your theory of Continental Drift.
• Use the evidence from the lab we just completed. Your reasoning you can come up with on your own (Remember it is 1915 and you are Wegener)
CER Peer EditingCER Peer Editing• Claim – All continents were once joined together and
have since drifted apart = 20pts
Is it a complete logical sentence = 10pts
• Evidence – Must mention at least 2 of the following:
Dinosaur Fossils, Plant Fossils,
Landforms (the way they fit together) = 30 pts
Is it a complete sentence? = 10pts
• Reasoning – Does it make sense? = 20 pts
Is it a complete sentence? = 10pts
Write the totals in the box at the bottom of the page