Parameter Tree:

Pertaining to geophysical (seismic, magnetic, gravity, etc.) data collected
on the plains and hills of the deep oceanic floor.
ABYSSAL HILLS: Small hills found only in the deep sea which rise from the ocean
basin floor with heights ranging from 10 to over 500 feet and widths from a few
hundred feet to a few miles. They are found along the seaward margin of most
abyssal plains and originate from the spreading of mid-ocean ridges. As such,
they usually form two strips parallel to mid-ocean ridges. They generally
decrease in height as one traverses away from the ridges as they gradually
become covered with sediment and are replaced by abyssal plains.
ABYSSAL PLAINS: Flat areas of the ocean basin floor which slope less than 1
part in 1000. These were formed by turbidity currents which covered the
preexisting topography. Most abyssal plains are located between the base of the
continental rise and the abyssal hills. The remainder are trench abyssal plains
that lie in the bottom of deep-sea trenches. This latter type traps all
sediment from turbidity currents and prevents abyssal plains from forming
further seaward, e.g. much of the Pacific Ocean floor.

Rhodes W. Fairbridge. The Encyclopedia of Oceanography. Van Nostrand
Reinhold Co., 1966.
Glossary of Oceanography and the Related Geosciences with References, Steven K.
Baum, Texas Center for Climate Studies, Texas A&M University, Copyright
1995-1996, January 20, 1997,