98
a
LONGSHORE
CURRENT
FAIRWEATHER
WAVE
BASE
WAVE
ENERGY:
DUNES
RIP
CHANNEL
FAIRWEATHER
HIGH
/'
\
Chapter 3 Coastal and Shallow Sea Sediments
TRANSPORT
OF SIL T AND CLA Y
INTO DEEPER WATER
c
+
-
SAND
BARS
1
/
/
/
PREDOMINANTL Y
1SEAWARD
ACCRETION
OF FORE SETS
WINTER
(STORM)
PROFILE
SHOREFACE:
ZONE OF CONTINUOUS
SAND MOVEMENT, BUT
± CLOSED SAND BUDGET
ICHNOFACIES
SKOLITHOS
- --- GENTLY SEAWARD DIPPING
LAMINAE OR LOW-ANGLE CROSS-B.
-:.,"%.; ....
+ DIFFEREN'T DIRECTIONS OF
CROSS-BEDDI~G
SAND 1"-' .... . . " .. \ .. ;o , f'"
;;: - :';.' :
" SANDY SIL T-CLAY
<;:= SEAWARD
Fig. 3.3. a Summer and winter (storm) beach profile,
offshore sand bars, longshore and rip currents. For
further explanation see text. b Sedimentary structures
of offs hore sand bars, generalized. (From various
sourees, e.g. Wemer 1963; Davis et al. 1972). Note
the prevailing landward dip of foresets. c Complete
synthetic vertical seetions of the shoreface-beach
zone of high- and low-energy shorelines, partly with
rip channels and offshore bars. Note the changing
orientation of foresets in different types of cross-bedding. (Based on Fig. 3.1, Elliott 1986, and others;
ichnofacies after Ekdale et al. 1984)