Chapter 12-Earth Science Flashcards
Who proposed the supercontinent
Alfred Wegener
Supercontinent called what and why
Pangaea
Pan means all
Gaea means earth
Evidence for continental drift
- fit like jigsaw
- matching geological structures and rocks
- fossil evidence
- climate evidence
Matching geological structures and rocks
Mountain ranges started on one continent and continue on another
Other continents have same rocks
Matching fossils
Mesosaurus was found on two different continents and couldn’t have swam across an ocean
Climate evidence
Coal in cold places
Glaciers in warm places
Paleoglaciation
Refers both to the extant of ancient glaciers and to the rock markings they left behind
Evidence for tectonic plates
- volcanoes & earthquakes
- continental drift
- sea floor spreading
- magnetism
Earthquakes and volcanoes
Plates boundaries determined by where they are
Volcanoes from friction
Earthquakes from plates rubbing
Sea floor spreading
By a underwater Ridge system newer rock in near the centre older is farther away
Molten hot rock breaks through the ridge
Land- Rift Valley ocean- spreading centre
Magnetism
Sea floor shows patterns of reversal and perfect mirror image on both sides
Three main layers of earth
Crust
Mantle
Core
All layers
Inner core-solid Outer core-liquid Asthenosphere-liquid/solid Lithosphere(m/c)- solid Crust-solid(basalt, granite)
Lithosphere
The layer of earth made up of the crust and the most solid part of upper mantle
Asthenosphere
A partly molten layer just below lithosphere. It sits on it
Convection currents
When heated material expands and rises plates push apart and when denser currents cool, sink the plates pull together
What heats up asthenosphere
Radioactive decay
Driving force behind plate movement
Convection currents
Divergent
-plates spread apart
-mid-Atlantic rid(spreading ridges)
Creates
. Spreading centre
. Mid-ocean ride
. Rift Valley
Convergent
Ocean/land
- plates collide
- dense ocean plate subduct under the the continental plate
- Juan de Fuca plate and North America plate
- volcanic belt, mountain ranges, deep sea trench
Convergent
Ocean/ocean
Two ocean plates collide the denser plate will subduct
- islands of Japan & Indonesia
- volcanic island arc, earthquakes, deep sea trench
Convergent
Land/land
When to land plates collide neither subduct
- indo-Australian colliding with Eurasian formed Himalayas
- mountain ranges
Transform
- slide past each other
- San Andrea’s fault: North American plate & pacific plate
- earthquakes, faults
Hot spots
Area where molten rises to earths surface
- Hawaiian islands
- volcanic islands
