Plate Tectonics and Seafloor Features

Flashcards covering plate tectonics, continental drift, seafloor spreading, evidence from land and sea, plate boundaries, and bathymetric features based on lecture slides.

What is the Oxford Languages definition of continental drift?

The gradual movement of the continents across the earth's surface through geological time.

What is the Oxford Languages definition of plate tectonics?

A theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates which move slowly over the underlying mantle.

Who proposed the hypothesis of continental drift and named the supercontinent Pangaea?

Dr. Alfred Wegener.

What are the three main lines of evidence from the land that support continental drift?

1. Jigsaw-puzzle fit of continents
2. Disjunct distributions of plant and animal species
3. Matching rock and fossil types on opposite shores

Which fossil organisms are cited as evidence for continental drift based on their disjunct species distributions across southern continents?

Mesosaurus, Lystrosaurus, Cynognathus, and the fossil plant Glossopteris.

Why was Alfred Wegener's hypothesis of continental drift originally rejected by many geologists?

While the evidence was impressive, Wegener could not provide an acceptable physical mechanism for how the continents moved.

Who proposed the concept of seafloor spreading, and in what year was it published?

Dr. Harry Hess proposed seafloor spreading, which was published in 1962 (the term 'spreading of the seafloor' was introduced by Robert S. Dietz in 1961).

What hypothesis did Frederick Vine and Drummond Matthews propose in 1963 regarding magnetic stripes on the seafloor?

The Vine-Matthews-Morley (VMM) hypothesis, which stated that alternating symmetrical magnetic stripes on either side of mid-ocean ridges act as a 'tape recorder' of Earth's magnetic field polarity reversals as new crust cools and spreads away.

Which research vessel confirmed seafloor spreading by drilling into ocean basins and dating sediment cores between 1968 and 1983?

The Glomar Challenger (during the Deep Sea Drilling Project, DSDP).

What are the four progressive stages of continental rifting at a divergent plate boundary?

1. Upwarping
2. Rift valley formation
3. Linear sea creation
4. Ocean basin / mid-ocean ridge creation

What modern examples illustrate a rift valley and a linear sea formed by continental rifting?

The East African Rift Zone represents a rift valley, and the Red Sea represents a linear sea.

What characteristic rock structure forms during volcanic eruptions along underwater mid-ocean ridges?

Pillow basalt.

Which volcanic rock types predominate in volcanic arcs along convergent subduction zones, such as Saipan?

Dacites (characteristically glassy) and andesites (comparatively crystalline).

What is the deepest point in the ocean, and what is its location?

Challenger Deep, located in the Mariana Trench in the Pacific Ocean at a depth of approximately $11,035$\,m.

What level of hydrostatic pressure is exerted at the extreme depths of the Mariana Trench?

$$8\text{ tons / square inch}$$

What is a guyot (or tablemount)?

A flat-topped seamount that was originally a volcanic island but was eroded flat by wave action as it submerged.

How did the Hawaii–Emperor Seamount Chain form?

By the Pacific Plate moving over a stationary mantle plume or hotspot.

What study on crustacean claws by Tshudy and Sorhannus (2000) is used to illustrate convergent evolution?

The independent evolution of pectinate (comblike) claws in four separate lineages of decapod crustaceans, such as the deepwater lobster Thaumastocheles and deepwater shrimp Ctenocheles.