(TD) Oscillatory Motion Flashcards
What is the definition of “Oscillatory Motion”?
No net sideways motion in a simple wave
What is wave height and energy determined by?
Strength of the wind and the fetch
What is the “Fetch”?
Expanse of water over which the wind is blown
What is the “Wave Base”?
The depth at which the circular cells created by oscillatory motion dies out
How do wave ripples relate to the wave base?
In shallow water, the wave base would be below the bed, thus energy is transferred into creating lateral movement along the bed
What do low energy wave ripples look like?
Rolling grain ripples - broad troughs and sharp crests
What do high energy wave ripples look like?
Vortex ripples - small clouds of grains swept from troughs to peaks - fall out of suspension
What is another name for a low energy wave ripple?
Rolling grain ripples
What is another name for a high energy wave ripple?
Vortex ripples
What are the three variable characteristics of wave ripples?
Straight/Sinuous crests, Laminae in both directions, Overlap
What is the principle grain size wave ripples form in?
Coarse silts to sands
Wave ripples can form in any ___ sediment
Non-cohesive
What wavelength would be expected in gravel ripples?
Several m
What crest height would be expected in gravel ripples?
10’s cm
What are the two primary differences between the formation of current and wave ripples?
Current ripples = any depth, wave ripples = limited to shallow depths AND current ripples = generall curved crests, wave ripples = generall straight to sinuous crests
