Chapter 3C Sections 1, 2, 3 MESSANA Science 8
Chapter 3CSections 1, 2, 3
MESSANAScience 8
Ocean WatersContains NaCl, dissolved solids & gases (O2, N2, CO2)
Salinity = 35g salt/1000g seawaterHigher salinity = higher density of
waterObjects are more buoyant in water
that is more dense (Dead Sea – 10X saltier than ocean->more dense ->humans more buoyant)
Buoyant Force vs. Gravity
3 Layers of Ocean1. Surface = warm water, less dense, coldest at poles, warmest at equator, 0-300 m, 25 C
2. Thermocline = temperature drops fast as depth increases, 300 – 700 m, 25->5 C
3. Deep = cold all year, barely above freezing, 0-3 C
Ocean Floor Features1. Continental Shelf = flat or gently sloping
land that extends underwater from the edges of a continent to a continental slope
2. Continental Slope = land that drops down steeply at the edge of a continental shelf
3. Submarine Canyons = cut through continental shelf & slope
4. Ocean Trenches = narrow, steep-sided clefts farther out in ocean floor, convergent boundary where old rock sinks down
Ocean Floor Features5. Mid-Ocean Ridge = chain of mountains
that runs through an ocean basin, divergent boundary where molten rock rises out of rift valley pushing old rock aside
6. Seamounts = underwater mountains (over a hot spot)
7. Volcanic Islands = underwater volcanoes tall enough to reach above the surface (Ex:Hawaii)
8. Abyssal Plain = wide, flat area of ocean floor covered with thick sediment layer
Ocean Floor Topography
Ocean Floor Topography
Ocean CurrentsCurrents = mass of moving water, distributes
heat & nutrientsSurface Currents – caused by WINDS
Top 200 metersRotate different directions in each hemispherePull warm water from equator & cold water from
polesGulf Stream = surface current that moves water
from the Gulf across Atlantic Ocean, northeastward toward Britain, makes climate there more mild
El Nino = change in surface currents in Pacific due to winds not blowing as strongly west across the Pacific, affects weather patterns globally
Surface Currents surrounding US
Ocean CurrentsDeep Currents – caused by DIFFERENCES IN DENSITY (due to temperature & salinity)
1. Upwelling: movement of water up to surface, brings up nutrients, good for animal life
2. Downwelling: movement of water from surface to greater depths, carries O2 down, allows for life
Upwelling & Downwelling
Exploring the Ocean FloorHow can we overcome ocean
obstacles to learn more?...PressureDarknessLack of airColdWildlife
Exploring the Ocean FloorTechnology to use:
SubmarinesSubmersibles (Alvin)Robots with camerasSonar = using sound waves to measure distances, depths, locate objects
Satellite Imagery – light waves from space
University of Miami Submersible
The Ocean Pearl
Sonar for measuring depth of ocean floor:
Satellite Image of Ocean Floor
http://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html