THE OCEANS

• 71% of the Earth’s surface is covered by oceans and seas

• water in the oceans formed by outgassing of volcanoes

• Waves1. created by wind energy

i. strengthii. the longer it blowsiii. greater distance that it blows (fetch)

2. swells - storm waves

• Waves3. water moves only slightly as waves pass by

i. wavelength - distance between crestsii. wave height - the vertical distance between the trough and

crestiii. period - time required for one wavelength to pass a set pointiv. wavebase - ½ of wavelength

• Waves4. breaking waves

i. when wave base equals water depth, the wave “feels bottom” and is slowed down

ii. as the wave slows, following waves press forward and decrease the wavelength between waves, thus increasing the wave height

• Waves4. breaking waves

iii. the wave becomes to high and steep so it breaksiv. as waves break, they form swash and backwash

(1) swash - rush of water toward the shore(2) backwash - return flow of water from the shore

(a) riptidesv. swash and backwash move sand grains onshore and offshore

• Waves5. Wave refraction - waves bend as they encounter shorelines

• Waves

5. Wave refraction - waves bend as they encounter shorelines

i. concentrates energy on prominences and dimishes it in bays

ii. smooths coastlines

• Waves

5. Wave refraction - waves bend as they encounter shorelines

iii. longshore drift - waves strike shoreline at an angle and push sand and other material along the shoreline

• Waves6. Tides

i. caused by gravitational attraction between the Earth and Moon that pulls water toward the Moon

• Waves6. Tides

ii. spring tides - Moon and Sun line up once a month to produce higher than average tides

iii. neap tides - when the Moon is in the 1st and 3rd quarter, the Moon and Sun are working against each other to produce lower than average tides

iv. tidal surges

• Waves6. Tides

iv. tidal surges

• Waves

6. Tides

v. tidal currents

(1) flood tides

(2) ebb tides

• Shoreline features1. beaches

2. offshore, foreshore, backshore

• Shoreline features

3. erosion and coastal forms

i. stacks

ii. wave-cut terraces

• Shoreline features

4. depositional coastal forms

i. spits

ii. barrier islands

• Ocean floor features - Atlantic Ocean1. Continental Margins

i. Continental Shelf (1) broad, flat plains of sand and mud

(1° slope)(50 - 200 m)(2) shelf-slope break

• Ocean floor features - Atlantic Ocean1. Continental Margins

ii. Continental Slope (1) steeper sloping than continental margin (4°)(2) Submarine Canyons

• Ocean floor features - Atlantic Ocean

1. Continental Margins

iii. Continental Rise

(1) gently sloping seafloor beyond the continental slope

• Ocean floor features - Atlantic Ocean

2. Sea floor

i. abyssal plain - at depths of 4000 - 6000 m

• Ocean floor features - Atlantic Ocean

2. Sea floor

i. abyssal plain - at depths of 4000 - 6000 m

ii. seamounts, volcanoes and guyots

iii. reefs

iv. Mid-Atlantic Ridge - rift valley

• Ocean floor features - Pacific Ocean

1. small continental shelf

2. Peru-Chile trench - 8000 m deep

3. East Pacific Rise - rift valley

4. Tonga Trench - 11,000 m deep

• Continental margins - shorelines, continental slope, and continental shelf

1. Active margins - close to plate boundaries

2. Passive margins - far from plate boundaries

• Continental shelves - $$$

• Continental Slope and Rise