4. Sonar
• An electronic depth-
sounding mechanism;
Sonar is an acronym
for sound navigation
and ranging. Sonar
calculates ocean
depth by recording
the time it takes for
an energy pulse to
reach the ocean floor
and return.
6. Key Concept
• How much of Earth’s surface is
covered by water?
–Nearly 71 percent of Earth surface is
covered by the global ocean.
7. Key Concept
• How can the world ocean be
divided?
–The world ocean can be divided into
four main basins- the Pacific Ocean,
Atlantic Ocean, Indian Ocean, and
Arctic Ocean.
8. Key Concept
• How does the topography of the
ocean floor compare to that on land?
–The topography of the ocean floor is as
diverse as that of continents.
9. Key Concept
• What types of technology are used
to study the ocean floor?
–Today’s technology particularly sonar,
satellites, and submersibles allows
scientists to study the ocean floor in a
more efficient and precise manner
than ever before.