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