Exercises: Plate tectonics
Explain what a lithospheric plate is and name three plates: one containing Europe, an American one, and one that is almost entirely oceanic.
Explain what a lithospheric plate is and name three plates: one containing Europe, an American one, and one that is almost entirely oceanic.
The diagram shows the three types of boundaries that can exist between two lithospheric plates. State which type of plate boundary (divergent, convergent, or transform)…
The diagram shows the three types of boundaries that can exist between two lithospheric plates. State which type of plate boundary (divergent, convergent, or transform) corresponds to each number and explain what happens to the plates in each case.
State whether the following statement is true or false and justify your answer: "Continents move because the lithospheric plates on which they rest move."
State whether the following statement is true or false and justify your answer: "Continents move because the lithospheric plates on which they rest move."
State and briefly describe two forces that contribute to the movement of lithospheric plates.
State and briefly describe two forces that contribute to the movement of lithospheric plates.
In subduction zones, one plate slides beneath another. Describe two geological phenomena associated with these zones and give a real example of a subduction zone.
In subduction zones, one plate slides beneath another. Describe two geological phenomena associated with these zones and give a real example of a subduction zone.
The San Andreas Fault in California is a transform plate boundary. Explain the relative movement of the plates at this type of boundary, what hazard it creates, and why…
The San Andreas Fault in California is a transform plate boundary. Explain the relative movement of the plates at this type of boundary, what hazard it creates, and why volcanoes do not form there.
Paleomagnetic and satellite measurements confirm that the Mid-Atlantic Ridge generates new oceanic lithosphere at a total spreading rate of about $2.5\ \text{cm/year}$,…
Paleomagnetic and satellite measurements confirm that the Mid-Atlantic Ridge generates new oceanic lithosphere at a total spreading rate of about $2.5\ \text{cm/year}$, which has enabled the widening of the Atlantic Ocean since the breakup of Pangaea.
- a) A student proposes the following deduction: "Since ocean ridges worldwide continuously generate crust, the volume and surface area of the Earth must have grown steadily over the last $200$ million years". Refute their hypothesis by explaining what process compensates for the creation of lithosphere and at what type of plate boundaries it takes place.
- b) If the current distance between the coasts of West Africa and North America at that latitude is about $4\ 500\ \text{km}$, estimate how many million years ago the Atlantic Ocean began to open in that region, assuming that the spreading rate remained constant.
- c) Predict and justify how the age of the rocks and the thickness of marine sediments will vary as you move from the ridge axis toward the African continental margin.