Internal Processes / Volcanism & Plutonic Landforms - Plate Tectonics
Continental
Drift / Plate Tectonics
- The Puzzle
- Alfred Wegener "Continental Drift" hypothesis
- obvious jigsaw puzzle
- Scandinavian & British Isles mountains matched Appalachian mtns.
- Mesosaurus fossils found in both South America and Africa
- Evidence
- oceanic mapping efforts
(1940's - 60's)
- Explanation (cause)
- concept of convection
to explain continental drift
- rise
of new crustal
material at mid-oceanic ridges
- conveyor belt movement
- now known as sea-floor
speading
- Plates and Movement
- 20
major plates moving as distinct units (see map)
- lighter continental
plates and heavier and thinner oceanic plates
- Diverge at
mid-ocean (divergence)
- diverge on continents
- Lateral movement
- plates slide past one another
- Converge where
plates slowly collide into one another
- South Asian Continent
- continental - continental convergence
- "Subduction"
- where plates slide under one another
- associated with volcanoes and earthquakes