Name: ___________________________________ Date: ___________________ Period: ______
Oceans: 20.2 Features of the Ocean Floor
1. The _________ floor can be divided into _______ major areas.
a. The _______________________ margins are shallower portions of
the ocean floor made up of continental _________ and a thick wedge
of ______________________.
b. The deep ocean ___________ is made up of oceanic __________ and
a ____________ sediment layer.
2. Continental Margins
a. ______________________ are not the true boundaries between the
________________ floor and the ____________________________.
i. The real boundary lies ______________________, beneath the
ocean and the ____________ sediments.
b. The continental ___________ is the part of the continent that is
_______________________ by ocean ____________.
i. In general, the ___________ of the shelf drops about ________
for every _________, and the _________ above the continental
shelf is about _______ deep.
ii. While the continental _________ is under _____________, it is
not part of the deep ocean ____________, it is part of the
continental __________________.
iii. The __________ of the continental shelf ___________ greatly.
1. On the west coast of South America, the _____________
shelf is only a few _________________ wide. However,
the ____________ continental shelves extend out about
_____________ from Siberia and Alaska into the Arctic
Ocean.
iv. During the _____________ period more of the continental shelf
was exposed to ____________________ and ______________
since so much water was in the form of _______, and currently
the continental shelf is a ________________ version of the land
surface above the ______________________.
c. A continental ____________ is a steep slope at the _______________
edge of a continental ____________.
i. The __________________ between the continental _________
and the ______________ crust is found at the base of the
continental ___________.
Name: ___________________________________ Date: ___________________ Period: ______
ii. Along the __________________ slope, the ocean ___________
increases to several thousand ___________ within a distance of
a few _______________________.
iii. Submarine _________________ are areas where the
continental ___________ and slope are cut by deep _________
valleys.
1. These ____________ are generally associated with the
mouths of major ______________.
2. However, some _____________ have been caused by
__________________ currents.
a. Turbidity ______________ are very ___________
currents that carry large amounts of ____________
down the continental ___________, and form
when ___________________ of various materials
run down a slope.
b. At the _____________ of the continental slope
these sediments are _______________ and form a
raised wedge called a continental ___________.
3. Deep Ocean Basins
a. The deep ocean _____________ have features such as ___________,
flat plains, submerged volcanic ________________, gigantic volcanic
_________________ ranges, and deep _________________.
b. On the deep ___________ basins, the mountains are __________ and
the ____________ are flatter than any found on the ______________.
c. ________________ are deep valleys in the ocean _________. In fact,
they are the __________________ features on the earth’s surface.
i. The deepest __________ in the world is the _______________
Trench, located in the western _________________ Ocean near
the island of Guam, and is over ______________ deep.
ii. Most _________________ are located near the __________ of
___________ and are associated with ___________________,
volcanic mountain ranges, and volcanic island _________.
d. __________________ plains are extremely ________ flat areas that
lie in the deep _____________ basins where the ocean depth is often
________________ than 4km.
i. ______________ plains cover about ___________ of the deep
ocean _____________ and are the flattest regions on earth.
Name: ___________________________________ Date: ___________________ Period: ______
e. ______-____________ ridges are a continuous series of underwater
mountain _______________ that run along the floors of all ________,
and in a few places, such as ______________, these mid-ocean ridges
actually rise above ______ level.
i. Mid-ocean _____________ form when plates _________ away
from each other.
ii. Along the _________ of the ridge are __________, which are
narrow ___________________ where magma reaches the sea
__________ and form the earth’s newest _____________ rock.
1. The new __________ is less dense and is ____________,
however when it cools it becomes more dense and moves
away from the __________.
2. Because different parts of the ____________ separate at
different rates, the new crust ____________ into a series
of ____________ called _______________ zones that
run perpendicular to the ___________.
f. ____________________ are submerged volcanic ________________
that are at least _____________ high.
i. ________________ volcanic mountains that are ________ than
1,000m are called abyssal __________.
ii. Seamounts that _________ above the _______________ of the
ocean form oceanic _______________ such as Hawaii.
iii. Both of these features are associated with _________________.
iv. As these ___________________ islands erode away and _____
back into the ocean they are called ________________.
1. _______________ are flat-topped, submerged
_________________ also called ___________________.