Ocean Floor / Earth Science

Which of the following correctly describes the Atlantic and Pacific continental margins?

The Atlantic is a passive margin, and the Pacific is an active margin

Choose the true statement regarding the continental shelf.

The shelf represents the flooded portions of continents.

Turbidity currents travel from the shelf through __________, creating deep sea fans.

canyons

If the subduction angle is steep, the overriding plate may undergo __________.

subduction erosion

Which of the following is true regarding shallow subduction angles?

Sediment and seamounts are scraped from the downgoing plate to produce an accretionary wedge

What happens as plates diverge at an oceanic ridge?

New oceanic crust and lithospheric mantle are generated by the cooling of molten rock upwelling from the
mantle.

What two layers of the ophiolite sequence are compositionally similar, but formed in different areas with respect to the
crust?

pillow lavas and gabbro

Which of the following contains the entire ophiolite suite, in order from the mantle to the seafloor?

mantle peridotite, gabbro, sheeted dike complex, pillow lavas, deepsea
sediments

What are the features associated with a divergent boundary that is spreading quickly?

a relatively smooth swell with gentle slopes

Which of the following accurately compares the MidAtlantic
Ridge and East Pacific Rise?

The MidAtlantic
Ridge is spreading at a much slower rate than the East Pacific Rise.

Name the correct order of rifting events.

crustal upwarp, rift valley, linear sea, ocean

The Gulf of Aden represents which part of the rifting sequence?

linear sea

The timing of __________ and continental breakup strongly correlate.

flood basalt formation

What feature connects the South American Paran� and African Entedeka flood basalts?

seamount chains

What sequence of rocks would you expect rift valley evolution to produce, from oldest to youngest?

volcanic rocks, clastic sedimentary rocks, deep sea sedimentary rocks

Which of the following is a true statement regarding the Farallon Plate?

It was an oceanic plate that used to exist between the Pacific and North American Plates

The plate boundary in the U.S. Pacific Northwest is _____, while most of the California coast is characterized by a _____
plate boundary.

convergent? transform

Which statement regarding Baja Mexico and the city of Los Angeles is correct?

Both are located on the Pacific Plate.

Strikeslip
faulting of the Queen Charlotte and San Andreas fault systems shows __________.

a right lateral sense of motion

What happened to the Farallon Plate approximately 20 million years ago?

The San Andreas and Queen Charlotte Faults were established where it was subducted beneath the North
American plate.

How is ocean depth calculated by sonar?

Ocean depth is calculated by the time it takes sound waves to travel from the ship to the seafloor and back to
the ship again.

What type of ocean exploration technique is the best for determining potential oil and gas reservoirs?

seismic reflection survey

Name all of the ocean bottom features shown in the image of the Los Angeles coast produced by the multibeam sonar.

shelf, canyons, slope, rise

Satellites record slight variations on the sea surface using radar. What do these slight variations represent?

features on the seafloor

Which of the following describes a seismic reflection survey?

Seismic signals produced from an explosion travel to the ocean floor, penetrate some layers, and reflect back
to a receiver.