Geology 1001-section 4
Dr. Dutrow
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OCEANS
(incomplete versions of overheads)
in five major oceans: Atlantic, Pacific, Indian, Arctic, and Antarctic - they discovered the rich topography of seafloor: - Most progress being made in the last 30 years due to new instrumentation and deep sea submersibles
EDGE OF THE SEA
    1. have a
    2. appear away from shore and eventually
    3. develop due to
    4.     - causes water to
    5.     -
    6.     - velocity = speed at which
    7.         e.g. 30 - 90 km/hr
    8.     -length = distance between
    9.     - height = distance from
    10.         e.g. ocean waves - 2 - 5 meters
    11. wave heights are a function of:

PATTERN OF WATER MOTION
(Note: wavelength - distance between adjacent crests or troughs, measured crest to crest or trough to trough)     - Swash (uprush of water) and backwash (back flow of water) can carry

- results in

- Change in wave motion as

    first arrival loses    , deeper water moves

- if swells approach at an angle, the initial waves

 

 

i.e. the water shallows more quickly and refracts

 

i.e. where wave energy is

water returns to sea perpendicular to

 

- Longshore drift - occurs when the swash and backwash

 

- Longshore current - shallow water current

 

- Rip current - "undertoe"; strong current

 

!!! swimmers hazard!!! to escape, swim parallel to shore

 

TIDES
  1. Earth - Moon:
        - High Tide - ocean facing

      - Low Tide - occur simultaneously on opposite

The Earth-Moon cycle is 24 hours and 50 minutes

 

2. Earth - Sun:

The Earth-Sun cycle is every 24 hours (length of solar day)

 

3. The nonsynchronous cycles and the slower lunar cycle means that

   - Rising tide elevated water           , advancing 
        =        tide

- Falling tide lower water

     =       tide

Distance between local low and high tide =

      0.5m in Hawaii; 20 m in Bay of Fundy

Tidal flats - muddy/sandy coastal between
    exposed at

4. Spring Tides - when Moon, Earth and Sun a

 

 

- highest tides occur every

 

5. Neap Tides - lowest tides occur when moon and sun are

 

 

   

SHORELINES
    Most significant factor is

    Where Energy is concentrated,               occurs

    Where Energy is dissipated,               occurs

- Beach budget consists of several

- Coastal Erosion - typical of tectonically uplifted rocky coasts

            erosion claims large areas of

            produces landforms: wave cut

    1. produces stacks - isolated
    2. terraces - wave cut
 
- Coastal Deposition - tectonically

        longshore currents transport sediment

    1. produces spits -
    2. barrier islands -
    e.g. Grand Isle, LA
!!! Beware of longshore currents and building on the beach!!!
Human induced Coastal Deposition

Man made structures disrupt

Breakwaters - walls to intercept

        result in

Groins - Shore-protection strutures perpendicular to

Jetties - extend stream channels
 


CHANGES IN SEA LEVEL
estuary formation- coastal body of water connected to ocean and supplied with fresh water from rivers.
 


STOP HERE!!!!
 
ANATOMY of an OCEAN FLOOR

Oceans are bounded by

 

1. Continental Shelf - shallow, submerged

 
-exception is tectonically
  1. passive margin - continental borderland far from
 
- consist of flat-lying

 

- e.g. such as Atlantic, opened 180 Ma, broken and rifted at margin by upwelling of magma

2. active margins - margins associated with

 

e.g. in tectonically deformed shelves, Pacific, typically a coincidence of

 

 

2. Continental Slope - regions of steep slope

 

   
 
  3. Continental rise - sediment apron at base of slope

 

4. Abyssal Plain - wide flat plain that covers large areas of

 

5. Seamounts - submerged mountain with
e.g. Bermuda - extends to surface, capped with
6. Mid-Ocean Ridge        
- U-shaped
- broader and shallower
7. isolated volcanic islands develop throughout the ocean floor e.g. Hawaii
 

TURBIDITY CURRENTS
         
DEEP-SEA SEDIMENTATION
 
- accumulate at

- may react with sea water to form

 

 
- Carbonate compensation depth: depth at which