23.1
KEY IDEA
Scientists have developed many
different technologies and
methods for studying the ocean
floor.
KEY VOCABULARY
• echo sounding
• core sampling
Studying the Ocean Floor
Submersibles, satellites, and other technology allow scientists to study the
structure and composition of the ocean floor.
Echo Sounding
In the days of the first oceanographic surveys, scientists measured the
distance to the sea floor with a lead weight on a line. They lowered the
weight until it touched bottom, measured how much line they had let out,
and then hauled the weight back up. In deep seas, a single depth reading
might take an entire day. This process was time-consuming and provided
limited information.
SINGLE BEAM
Single
beam
sound
signal
from
ship
MULTIPLE BEAM
Multiple
beam
sound
signal
Signal
echoes
back to
ship
Sea floor
ECHO SOUNDING Single beam soundings provide the depth only along a ship’s course,
while multiple beams measure depth over a much larger area.
CLASSZONE.COM
What Does the Ocean Floor Look
Like? Drain the oceans and explore
the mountains, valleys, and volcanoes
of the sea floor. Examine some
features and explain how they formed.
Keycode: ES2301
510
Unit 6 Earth’s Oceans
Today ships use echo sounding, or sonar, to find the distance to the
ocean floor. A special device called a precision depth recorder sends a
sound signal through the water to the sea floor. By tracking how long it
takes for the signal to reach the bottom and echo back to the ship,
scientists can measure the water’s depth. The recorder traces a continuous
profile of the area over which the ship is sailing. Such profiles help
oceanographers make accurate and detailed maps of the sea floor.
Multi-beam echo sounding allows scientists to cover an area that is up
to twice the depth of the water over which the research vessel is traveling.
Accurate maps can be made more efficiently and thus be more readily
compared with previous maps.
Scientists can also measure the intensity of reflected sound beams to
determine sea floor composition. For example, rock and gravel reflect
sound waves more strongly than mud. Then scientists may combine