Topic/Objective:_______________
_____________________________
_____________________________
Essential Question:
Full Name: _______________________________
Class: ___________________ Period: _____
Date: _________________
Ocean Floor (Chapter 23)
Tutor Use
Only:
Studying the Ocean Floor: Submersibles, satellites, and other technology allow scientists to study the _____________________ of the ocean floor.
1. Echo Sounding:
 a system that uses ____________________ and _________________ sound waves to measure distances to the ocean floor; SONAR o measure how long it takes for signal to be emitted and come back
 multi-beam echo sounding measures area ____________ as wide as ship

_______ info to make ________________ maps

Intensity of sound beams determines seafloor ___________________ o rock & gravel reflect more strongly than mud
2. Sediment Sampling:

Core sampling: hollow cylinder remove long ___________ of material from seafloor o layers are preserved o 1-1500m of sediment are gathered o Can analyze past ___________, __________, and __________ events

Essential Question:
Summary:
3.
Satellite Observations:
 greater range & speed for mapping
 doesn’t reach floor, bounces of surface
 Ocean _______________ varies based on what’s below o _____________ over mountains, ____________ over trenches o Determines differences down to ___________ o Makes high-resolution seafloor image
The Continental Margin
In order to understand the continental margin, we must first understand the
________ of the Earth. The continental margin is part of the __________.
Layers of the Earth: there are ____ main physical layers.
Crust: ___________.
Mantle: ____________ with liquid properties
Outer Core: liquid
Inner Core: solid
Continental Crust:

There are two types o Continental Crust
 lighter, ____________ dense rock
 makes up all _________________ but not necessarily all ______________ o Oceanic Crust
 darker, _________ rock
 any ___________ floor or ocean basin

Moving Crust o all of the crust is divided into ‘pieces’ or _________
 called lithospheric plates or ___________ plates) o the plates move around on the semi-solid____________ o where the plates meet or connect are called ____________ boundaries o at plate boundaries, the crust can be moving ________ by
_________, _____________ or ______________

Essential Question:
Summary:
1.
2. different topographic features are created, depending on the type of boundary topography: the ____________ of the land

Continental Margin: the ______________ portion of the continental crust.
o Parts of the continental margin
1.
continental shelf: part of the continent that extends from the __________________ to the continental slope

_________, lengths vary depending on location
2.
continental slope: begins at the ____________ edge where water depth increases rapidly to the rise.

20 km long, descends 3.6km
 sediments build up temporarily, then falls
3.
continental rise: _______________ gradually from the slope to the ocean floor
 considered part of ocean basin
 very long & gradual

Essential Question:
Summary: o Types of Continental Margins
1.
__________ Continental Margin
 continental ___________ that occur along a plate boundaries
 plates are moving ______ by _______ or together o when one plate sinks under another a
_____________ is formed o when plates move past each other, a
_________ is formed
 continental __________ is small or nonexistent

___________, short beaches with cliffs

___________, coastal mountains on land

Ex: West coasts of North America and South
America
2.
_____________ Continental Margins

Continental margins that ________ occur along plate boundaries

________ continental shelf

________, sandy beach

_____ trenches, mountains, or faults
 Ex: East coast of North America

Essential Question:
Summary:
Ocean Floor Features:

Submarine Canyons o an undersea gully that ________ across the continental shelf and slope o rivers __________ the continental _______ and ___________ sediment on the continental _________ o ____________ and powerful ______________ currents carry sediments down to the continental _________
 very powerful agents of ___________ o coarse particles settle first, then fine particles such as clay

Ocean Basin o ____________ plain: ___________ of all Earth’s surfaces, composed of sediments from continents
 occurs in all oceans
 more in ______________ Ocean where there are fewer trenches o ____________ hills: small hills, occur in groups next to
_______________ ridge systems.

Deep-Sea Trenches o long, narrow, steep-sided
_____________ that run parallel to continental margins or to volcanic island chains called island arcs
 exist at subduction zones
 common site of earthquake and volcanic activity

Essential Question:
Summary: o a marginal __________ forms if one plate is ______________ and the other is ________________.

If the oceanic plate _____________ below the continental, a line of volcanoes stands on the overriding continental plate, forming mountain chains

If both plates are ______________, an arc of volcanic islands form on the overriding plate

Usually in western Pacific Ocean
Oceanic plate descends below the continental plate
Oceanic plate descends below the oceanic plate

Vents and Ridges o Deep ocean vent – geyser that ________ underwater, mixing hot and cold water and bringing up minerals from beneath the surface

Essential Question:
Summary: o Mid-ocean ridges – are undersea
______________ ranges, form at divergent plate boundaries where 2 plates are moving apart an magma is rising

Sea Mounts and Guyots o ______________ are cone-shaped mountain peaks that rise high about the ocean floor

Occur in all oceans, but more abundant in Pacific Ocean

Volcanic in origin (ex. Hawaiian Islands) o ____________ are flat-topped seamounts

Waves remove their tops when they rose about sea level

Coral & Coral Atolls o Corals are tiny sea animals that live in shallow, warm waters.
Reefs form when new corals grow on top of dead ones o Coral Atoll is a _______________ coral island. It forms when a coral reef develops around a volcanic island. The mountain sinks below the water, leaving a circular reef with a lagoon where the mountain was.
Ocean Floor Sediments

Sediments reaches the ocean floor in several ways: _____________ currents, fall from above, settle from ____________, remains of microscopic __________

_______________ sediments – come from ____________ rocks and minerals broken down from weathering and erosion o wash into rivers and out to sea o may come from glaciers breaking and dropping into sea

_______________ sediments – come from ___________ sources; they are oozes made mostly of shells and skeletons from tiny marine animals o calcareous ooze = calcium carbonate
 most common from shells and skeletons
 dissolve as they sink below 4500 meters o siliceous ooze = silicon dioxide

More common around Equator and Antartica

Essential Question:
Summary:

_______________ sediments form when chemical reactions cause minerals to crystallize from seawater. o Manganese nodules are most common – has manganese, iron oxide, nickel, cobalt, copper… o they form on the sea floor from sediment that falls on them and mixes with the sea water, a few mm every million years o important to humans but hard to get
Importance of Sediments:
 by studying the layers of sediments in the ___________, scientists can determine: o the extent of former __________ ice sheets o the history of water _____________ on sea floor o the past behaviors of prevailing _____________ o pattern of ____________ in Earth’s climate
 the ______________, unique organisms, magnetic record, industrial resources on the ocean floor represent a __________ look at Earth’s hydrosphere, biosphere, and geosphere.