Inv 6 volcanoes and earthquakes Flashcards
How many major plates are there?
7
How many minor plates?
8
Convergent boundary
2 plates moving toward each other
Divergent boundary
2 plates moving away from each other
Transform Boundary (Strike-Slip)
2 plates sliding past each other
Plate interactions can form. . .
Landforms ( mountains, volcanoes, deep-ocean trench, rift valley, mid-ocean ridge)
Because volcanoes and earthquakes are caused by plates interacting with each other, they are most often found. . .
At plate boundaries (Ex ring of fire. along the pacific plate boundary)
Alfred Wegener
a German scientist and meteorologist who developed the theory of continental drift.
He theorized that the continents as we know them today were once part of a supercontinent known as Pangaea.
Evidence Supporting Continental Drift: Continent coastlines fit together like pieces of a jigsaw puzzle
if scientists could push the continents back together, they would see that they fit together like pieces of a puzzle due to their corresponding physical features
Ex. East coast of South America fits together with West coast of Africa.
Evidence Supporting Continental Drift: Animal fossil evidence
Fossils of the same types of animals were found on different continents
This suggests that the continents were together as one land mass at one point in time because the animals were able to roam freely throughout the supercontinent
Evidence Supporting Continental Drift: Plant fossil evidence
Fossils of the same types of plants were found on different continents
This suggests that the continents were together as one land mass at one point in time because plants cannot reproduce when there are vast oceans separating the continents.
Evidence Supporting Continental Drift: Living plants/animals
The same types of living animals can be found on different continents. This suggests that a common ancestor once roamed Pangaea, were separated by the separation of the continents and evolved to fit their new environment.
Another example is the fact that organisms such as mice, rabbits, and wolves all live on different continents.
Evidence Supporting Continental Drift: Geological Evidence
Evidence such as that suggest the continents were once together as one:
- mountain ranges,
- rock deposits,
- glacial striations (evidence that glaciers once moved over an area),
- mineral deposits,
- coal deposits that suggest the continents were once together as one.
Example of coal mine evidence:
European coal mines matched up with coal mines in North America
Evidence Supporting Continental Drift: Paleomagnetism (includes sea-floor spreading)/ Polar Wondering
–Magnetic field direction of Earth’s rocks/sediments
-evidence for new rock-forming at a divergent boundary
–Seafloor spreading confirms that continents are changing positions over time.
