The Ocean Floor and its Features
Summary
Students will use models to gain an understanding of the ocean floor and its features in
comparison to the continents.
Learning Objectives
Students will be able to:
 Assemble and draw features of the ocean floor
 Identify features on the ocean floor that are similar to features on land
Background
This lesson focuses on the physical features of the ocean floor as well as emphasizing
how vast the living space is within the ocean. Three web sites have been outlined and
provided below for the background information for the activities.
Here are some fun facts about the features on the ocean floor:
http://www.fathom.com/course/10701050/session1.html
 Introducing the ocean
o Scientists once thought the ocean was lifeless
o Ocean is populated down to its depths with life
o Oceans provide about 170 times the living space of all other Earth
environments combined—soil, air and fresh water
o Ocean features
 Continental Shelf—1/20th of total area of the oceans
 Continental Slopes—vary in steepness
 Abyssal plain—largest single environment on the planet with over
half of the ocean’s surface with depths down to 6,000 m
 Trenches—depth down to 10-11 kilometers!
 Mid-Oceanic Ridge—vast interconnected mountain chain
o Sea water
 35 gms of salt for every liter of water
 90% of the salt is sodium choloride
 Salinity remains quite constant allowing life to cope
physiologically
http://www.mos.org/oceans/planet/features.html
 Ocean planet
o 71% of planet covered by water
 Ocean facts
o Volume of the ocean = approx. 1.3 billion km3 (310 million cubic miles)
o Average Depth = 3,790 meters (12,430 feet or 2.35 miles)
o Deepest Point = Mariana’s Trench (estimated to be 10,971 meters deep or
35,994 ft or 6.8 miles)
o Mountains = mid ocean ridges, seamounts
o Highest Mountain = Mauna Kea in Hawaii (9,449 meters or 31,000 feet or
5.87 miles)
o Longest mountain range in the world = Mid ocean ridge
 Physical features
o Continental shelf = extended perimeter of each continent
o Continental slope = underwater feature that connects the continental shelf
to the abyssal plains
o Abyssal plains = underwater plain on the deep ocean floor, usually found
at depths between 3000 and 6000 meters.
o Mid-Ocean Ridge = underwater mountain system that consist of several
mountain chains; associated with divergent plate boundaries where two
oceanic plates spread apart; oceanic crust is created at mid-ocean ridges by
the eruption of lava onto the seafloor
o Seamounts = mountain rising from the ocean floor that does not reach the
water’s surface
o Guyots= tablemount; isolated underwater seamount with a flat top over
200 meters below the ocean surface
o Trenches = hemispheric-scale long but narrow topographic depression on
the seafloor; the deepest parts of the ocean; associated with convergent
plate boundaries where two tectonic plates come together; also associated
with volcanic island chains
http://www.ceoe.udel.edu/deepsea/home/home.html
 Three major regions of the ocean
o Continental shelf
o Continental slope
o Deep ocean basin = abyssal plains
 Hydrothermal vents
o Also called “geysers of the deep”
o Discovered in 1977
o White smokers = hydrothermal vent that emits light-hued minerals like
those containing barium, calcium and silicon; usually have lower
temperature than black smokers
o Black smokers = hydrothermal vent that emits dark-hued minerals like
metal sulfides
o Form in some areas along the Mid-Ocean Ridge
 High-Tech Tools
o Brief History (included in link above)
o Alvin and Atlantis = underwater vehicles for deep ocean research
o Other tools used for deep ocean research (included in link above)
http://www.livescience.com/14045-microbes-ocean-crust-observations-bacteria.html
 Extreme environments where life has been found
o Polar ice
o Hydrothermal vents
o Ocean aquifers—vast, hot, rocky environments within the Earth’s crust
beneath the ocean floor
http://www.marianatrench.com/mariana_trench-oceanography.htm
 Ocean Trenches
o Arctic Ocean’s Eurasian Basin at 5,450 m (17,881 feet) deep
o Indian Ocean’s Java Trench at 7,725 m (25,344 feet) deep
o Atlantic Ocean’s Puerto Rico Trench at 8,648 m (8,374 feet) deep
o Pacific Ocean’s Mariana Trench at 11,033 m (36,201 feet) deep
Pretest:
Give students a piece of blank paper and have them draw or color how the land and the
water meet. Students should include the bottom of the ocean in their picture.
Procedure:
 Show the key to the students
 Pass out the cutouts to the students
 Students should use the key and the cut outs to color the pieces, assemble them and
glue together the pieces
 Talk about the model
o What does the blue represent?
o Where is the land?
o Where is the top of the ocean?
o What do you notice about what is under the ocean?
o What looks familiar?
o What are the black poofs?
 Hand out the words to the students
o What words do you know on the page?
o Use PowerPoint presentation or diagram to label the features one at a time
o As you label each feature, ask students to figure out which definition
matches that vocabulary word (this enables them to deduce from the
picture what the vocabulary words mean)
o Show rest of PowerPoint presentation with pictures of underwater features
and land features
o Compare/Contrast the continental and oceanic features
Post-Test:
Have students draw the ocean floor again and label the features
Ocean model vocabulary
Definitions
Continental Shelf
mud or runoff soil
Continental Slope
mountain or hill by itself
Abyssal Plain
geyser
Trench
canyon or gorge
Aquifer
steep slope
Sediment
mountain chain
Hydrothermal Vent
gentle slope
Mid-Ocean Ridge
flat land
Sea Mount
porous rocks in the crust
Full definitions
Continental Shelf—extends underwater from each major landmass, slopes gently to
depths of about 200 m (650 feet) and varies greatly in width from the continent but the
average distance is 64 km (40 miles). Has features similar to those on land like hills,
ridges and canyons
Continental Slope—extends from the continental shelf descending rapidly down to the
deep ocean basin, from 200 m (650 feet) to 3,700 m (12,000 feet).
Abyssal Plain—average depth of 3,500—4,000 meters; almost imperceptible slope,
largest single environment on earth.
Trench—long and deep canyon-like gashes in the sea floor at least 6,000 m deep. The
deepest trench is called the Mariana Trench. The earth’s crustal plates are pulling apart
and the trench covers an area 2,542 km (1,580 miles) long, 69 km (43 miles) wide and
11,033 m (36,201 feet) deep.
Hydrothermal Vent—springs like geysers that spew out fluids with chemicals and
minerals from the underlying salt water aquifers
Mid-Ocean Ridge—Earth’s longest mountain range lies under the sea called the Midocean Ridge at 56,000 km (35,000 miles) long.
Seamount—a single mountain on the abyssal plain that remains below the sea surface
Aquifer—porous rocks below the surface of the ocean floor. Ocean water is sucked into
the crust, flows through the fractured rock and is eventually spewed out at hydrothermal
vents