Wave Dominated Depositional Environments - Beaches to Nearshore Marine Flashcards
1
Q
Offshore (Below wave base):
A
- Turbidity Currents + sediment settling, but no waves
2
Q
Offshore transition zone: is mostly off-shore expect during big storms
A
- biggest waves will produce hummocky-cross stratification
3
Q
Fairweather wave base
A
- everyday waves affecting the sea base
- cross beds everywhere showing the oscillation
4
Q
Shore-face
A
- above fair-weather base so constantly modified by waves (slope of shore)
5
Q
Low-tide
A
- next big boundary - subaerial and can dry out
6
Q
Foreshore
A
Between high or low tide
7
Q
Backshore
A
- mostly above high tide but the highest storms might reach it. May or may not be dunes behind it. Mostly dry
8
Q
Dunes
A
- Definitely dry, dominated by wind currents
- Wind is a current (not oscillating)
9
Q
Foreshore:
A
- Swash zone between high and low tide
- Upper plane bed parting lineation’s in a beach swash zone
- Coarse grain berm where fair-weather waves can’t reach them
- Planar bedding that is in the slope of foreshore
- Storm berm (long linear hummock where large debris collects
- Slope of the beach/foreshore forms planar beds with a slight dip
- Beds composed of very well sorted sediments due to constant back and forth motion
10
Q
Shore face Model
A
- Zoned by processes and relevant sedimentary structures
- Wave base: oscillating energy touches the sea floor
- shoaling effect: works the sediment and the friction starts to slow it down
- Getting slowed down compared to the motion at the surface results in oversteepening
- Friction slows basal wave propagation - top still moving along -> wave itself steepends and breaks
- Where shoaling you expect to have oscillating movement
- in the breaking zone and surfing you expect to have long shore currents
- Surf zone has a trough
- Expect to see currents modifying in these areas
11
Q
3 Controls of beach environments:
A
- Strength of waves
- Strength of tides
- Grain sizes available
