Tectonics Flashcards
Who was the German scientist who published the theory of continental drift? And at in what year?
Alfred Wegener, 1912.
What is a hot spot?
A point on the surface of the earth located above a plume of rising magma. The Hawaiian islands lie above such a spot.
What is a tectonic plate?
The lithosphere (the crust of the earth and the upper part of the mantle) is divided into a number of segments known as plates. These rigid slabs float on the underlying semi-molten mantle (asthenosphere) and are moved by convection currents within it.
What are seismic waves?
Shock waves released by the rupture of rock strata at the focus of an earthquake. They travel through the rocks and are measured and recorded on a seismograph.
What is a tsunami?
Sea waves, which can be very large, generated by shallow-focus underwater earthquakes (the most common cause), volcanic eruptions, underwater debris slides and large landslides into the sea.
What are the differences between continental and oceanic crust?
Continental crust is much thicker (being 30-70km thick whereas oceanic is 6-10km), Continental is older (over 1,500 years old) continental crust is lighter than oceanic.
What are the features of constructive plate margins?
Ocean trenches (mariana trench) - sea floor spreading (proof of continental drift). Shows how plates move away from each other.
What are the three layers of the earth?
The core (divided into the inner and outer core), the mantle and the crust.
What is the core made out of?
Iron and nickel
What is continental crust composed of?
igneous, metamorphic and sedimentary rocks.
What is oceanic crust composed of?
Manly basaltic in nature.
What is the basic form of evidence that supports the continental drift theory?
Continental fit - some continents seemed to fit together (i.e. Africa and South America).
What is the geological evidence that supports the continental drift?
Rocks of the same age, type and formation are found in SE Brazil and South Africa
mountain formations are similar in Eastern USA and NW Europe
glacial deposits are similar in Antarctica, South America and India.
What is the climatological evidence that supports the continental drift?
Antartica, North America and UK all have coal deposits of a similar age formed in the same tropical zones during the carboniferous period.
What is the biological evidence that supports the contental drift theory?
Similar fossil formations are found on either side of the Atlantic. Similar plants and animals found in coal deposits in India and Antarctica.
