Amott and Southard (1990), in a collinear oscillatory and combined 

 flow water tunnel with a wide range of component speeds and an oscilla- 

 tion period of 8.5 sec, have produced stability fields for wave-generated 

 bed forms in very fine sand. Figure 15 shows that different types of bed 

 forms and resulting internal stratigraphy are formed according to different 

 wave oscillatory speeds, which are greater closer to shore and reduce in 

 an offshore direction. 



Hummocky 

 Ripples 



10 cm Scale In 

 ^ Sketches 



Rot Bed 



0.08 0.12 0.18 0.20 



(Measured 0.10m Above Bed) 

 Unidirectional Speed (m/a) 



Figure 15. Stability fields for bed forms produced in very fine sand in collinear 



combined-flow water tunnel. Velocities were measured at 0.10 m above the 

 bed. Note that "2D" considers a two-dimensional (straight-crested, which is 

 usually representative of low energy conditions) bed form, while "3D" 

 considers a three-dimensional (sinuous-crested, usually representative of 

 high energy conditions) bed form (from Arnott and Southard (1990)) 



54 



Chapter 4 Sedimentary Features/Stratigraphy of the Inner Shelf 



