Chapter 3C Sections 1, 2, 3 MESSANA Science 8

Ocean Waters Contains NaCl, dissolved solids & gases (O2, N2, CO2) Salinity = 35g salt/1000g seawater Higher salinity = higher density of water Objects 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 Ocean 1. Surface = warm water, less dense, coldest at poles, warmest at equator, 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 Features 1. 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 Features 5. 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 Currents Currents = mass of moving water, distributes heat & nutrients Surface Currents – caused by WINDS Top 200 meters Rotate different directions in each hemisphere Pull warm water from equator & cold water from poles Gulf 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 Currents Deep 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 Floor How can we overcome ocean obstacles to learn more?... Pressure Darkness Lack of air Cold Wildlife

Exploring the Ocean Floor Technology to use: Submarines Submersibles (Alvin) Robots with cameras Sonar = 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

/asia/satellite-photos-japan-before-and-after- tsunami.html