Lesson 3 - Bathymetry of the Ocean Flashcards
What does bathymetry refer to in the context of ocean basins?
The shape of an ocean basin
What causes the deposition of sediments to the seafloor?
Erosion of the continents and erosion of submarine canyons due to currents
Where are deep ocean trenches mainly found?
At the margins of the ocean basins
What lies in between mid ocean ridges and deep ocean trenches?
Abyssal plains
What are the two types of continental margins?
Atlantic-type (passive margins) and Pacific-type (active margins)
What characterizes passive margins?
Wide continental shelf, little earthquake activity
What characterizes active margins?
Deep trench, active earthquakes, subduction zone
What are microcontinents?
Areas of continental crust that break off from a larger continental mass
What is the ‘ring of fire’?
A region surrounded by destructive plate boundaries characterized by seismic activity
What are back-arc basins?
Underwater volcanoes caused by the subduction of ocean crust into the asthenosphere
What percentage of the total oceanic area is made up of abyssal plains?
42%
What are abyssal plains primarily covered in?
Thick layers of sediments
What two sources supplement the sediments on abyssal plains?
- Erosion from continents
- Pelagic sediments from decaying animals and plant matter
How can the age of ocean crust be estimated?
From its depth
What are seamounts?
Submarine volcanoes that generally do not break the sea surface
What are oceanic islands?
Seamounts that break the sea surface
What are flat-topped seamounts called?
Guyots
How are guyots formed?
They are eroded flat on the upper surface by wave action
What is a mantle plume?
An area of high activity in the mantle
