Download Ch 11 Notes File

Science 8: Chapter 11 Notes
11.1 Ocean Basins
- oceans are _______________ into which water has flowed and accumulated
- oceans control Earth’s temperature, create weather patterns, and are the source of the
water that falls as fresh water on land
Features of the Ocean Floor
-
Two distinct parts: ocean basin and the rising outside edges called
______________________________
-
The greatest influence in shaping the ocean floor is the movement of the Earth’s
crust as a result of tectonic processes
o
Two types of plates: __________________ and continental
o
When two plates are pushed apart, the magma oozes up into the empty space
and creates a _____________________
o
When two plates are pushed together the denser ocean plate slips
underneath the continental plate (called ____________________) and an
ocean trench is formed
o
Between areas of trenches and ridges are wide, flat areas called
______________________________

Broken by underwater peaks called _____________________ (old
volcanoes)
-
Continental margins are made up of continental shelf (a flat area that extends from
the shoreline to the ocean basin) and the continental _______ (a steep area that
drops off rapidly to the ocean basin)
o
Sediments build up along the steep continental slope and the resulting
collapse creates a turbidity current (underwater landslide)

Deposit gently sloping piles of sediment that form the
_______________

Some are strong enough to create submarine ______________
11.2 Ocean Currents
-
A large amount of ocean water that moves (like a river) in a particular and
unchanging ___________________
o
More than 20 major currents in the world that transport huge quantities of
dissolved minerals, solar energy, oxygen and carbon dioxide as well as fish
and plankton
Surface Currents
-
Direction and speed of surface currents is directly connected to the direction and
speed of the wind blowing over the water and hot and cold air rising and
__________________
-
Spinning of the Earth on its axis affects both winds and ocean current
o
Spins west to east so the winds and currents get deflected right (east) in
the northern hemisphere

-
Called the _______________________
Continent shape and placement affects how and where surface currents will move
Deep Currents
-
Dense, cold water tends to sink beneath warmer water and then move along the
ocean floor
o
Called a __________________________
o
Three different layers to ocean water: the surface (Sun’s energy heats the
water), the ________________________ (water temperature drops
rapidly here), and deep water
-
The amount of salt in ocean water also contributes to the movement of density
currents
o
_______________________ is denser than water with low salinity

Areas near melting ice or near huge rivers are less saline

Increased salinity results from evaporation and freezing

The saltiest, coldest and densest waters are found at the North and
South Poles
-
Eventually the dense, cold water will be warmed enough to rise or pushed up by
colder, denser water from below
o
Called _______________________ which brings nutrient-rich waters to
the surface
Ocean waves and how they shape the land
-
Large, rolling waves that form in open oceans are called swells and as they reach
shallow water, they become “breakers”
-
Huge waves called _____________ are created by underwater earthquakes
-
Waves can erode even the rockiest cost and deposit huge amounts of sediment on
shores
o
Softer rock erodes more readily from waves and the sediment carried in
them
o
_____________________ are sections of the coastline that extend out
into the ocean (harder rock)

o
Can create interesting features like sea stacks
_______________ are indented areas where more deposition occurs
Tides
-
The daily cycle of rising and falling ocean water is called the tide and they are
caused by the gravitational attraction between the Earth and the Moon
- the difference between high tide and low tide is called the ________________
- if the Sun and Moon are both lined up then you get an extra high tide called a
__________________________ (occurs twice a month)
- if the Sun and Moon are not lined up then you get less extreme tides called
_________________________________
11.3 Oceans and Climate
- Heat capacity is a measure of how long it takes for a material to heat up or cool down
- water takes a long time
- Ocean and atmosphere are constantly exchanging water through the water cycle and
this exchange produces ____________________
- weather can be described in terms of temperature, wind speed and direction, air
pressure, and moisture
- weather that is averaged over a long period is referred to as __________
- through the process of convection, the Sun heats the surface of the ocean and some of
the heat is transferred to the air above which starts to rise
- mass of warm air is called a __________________
- as the thermal gets higher it starts to cool then sink back to the surface where
it gets reheated and starts to rise again
- in an El Nino year the water off the coast of Ecudor and Peru stays unusually warm for
months and this transfers into other parts of the world
- droughts and fires in Australia, Africa and Central America
- warmer ___________________________ in North America
- fish go to deeper, cooler waters so fishing is affected
- in a La Nina year, colder than normal waters come to the surface off the coast of South
America and we get wetter than normal periods
Moderating Effect of Oceans
-
Because of water’s high heat capacity, oceans stay warmer through the fall months
and into the winter
o
The _________________ causes the British Isles and Northern Europe to
be warmer than should be expected from there latitude
o
Coastal areas stay milder during winter

Coastal mountains prevent moist ocean air from reaching the interiof
of BC