48
INDIVIDUAL FLUVIAL SYSTEMS
± UNIFORM SAND/ MUD RATIO
I
I
I
I
I
I
I
I
/
/
a
b
Chapter 2 Continental Sediments
FLOODPLAIN, SMALL CHANNELS
AND LAKE DEPOSITS
UPWARD DECREASE IN SAND / MUD RATIO
"'- "- "'- "'- "'- "- "'- "- "'- "- "- "- "- "- "2
~@'2
MUD TO
PEBBLY SAND TO
SAND
CLAY
SANDY GRAVEL
c
SIMULTANEOUS AGGRADATION
CHANNEL FILL, LEVEE AND
CREVASSE SPLAY SANDS AND SILTS
PEAT
OF CHANNEL AND INTERCHANNEL
DEPOSITS
(LATER COAL)
~ 1 aOOm -----i
LACUSTRINE MARL OR
LIMESTONE, ± FOSSILS
Fig. 2.19. Large-scale cross sections of fluvial systems. a Generalized cross section of Cenozoic
coastal plain, Texas, demonstrating the major
depositional elements. b Close-up of a displaying
bedload river deposits which form a wide sand belt.
INCISED
CHANNEL
........ ":: .. ;: ....... :::, .. -, -.,'-. '''::::::::::.
FLOODPLÄIN
SILTS AND CLAY
(After Galloway 1981). c Idealized channel and
interchannel-backswamp-Iake deposits of a mixedload meandering system. (Based on Flores 1981;
Galloway and Hobday 1983). See text for further
explanation