CHARACTERIST ICS OF SHOREFACE STORM DEPOSITS: MODERN AND ANCIENT EXAMPLES 1

depths ranging between 5 and 21 m, contain a distinctive three-part sequence; from base upward consisting of: (a) basal lag, up to 50 cm thick, containing coarse gravel; (b) finely laminated sand up to 2 m thick, having median diameters ranging from 0.210 to 0.125 mm, and (c) burrow-mottled sand coarser in size than unit (b), up to 30 cm thick. The boundaries between (a), (b), and (c) are sharp. The relatively coarser, mottled sand composing the upper part of this sequence results from processes operating in the shoreface zone during fair weather. Such processes create either wave-ripple laminae (between wave base and the breaker zone) or burrow-mottled sediment (seaward of wave base). The lower part of the sequence is inferred to result from storms. The basal gravel is interpreted as a lag formed during maximum storm intensity when the coarse material is jostled at the bottom and the finer sediment is kept dispersed or is in turbulent suspension. The finely laminated sand is inferred to have been rapidly deposited under conditions of intense bottom shear as the storm waned