Growth of Present-Day Concepts, up to 1977
C c COLLWIAL OEPOSITS ALONG VALlEY SlOES
Vd • VERTICAL ACCRETION DEPOSITS
/.(!} • LATERAL ACCRETION 0EPOS1TS
.5 • SPLAYS ALONG fllLEO CHANNEL
k • TRENCHED TR!9UTARY VALLEY
p • CHANNEL FILL
t:) " ALL!JVIAL fANS
25
Fig. 2.11. A fluvial block-diagram model: "diagram illustrating typical relations of the various types of deposits in the
valley accumulation". (Happ et aL 1940)
the fi ning-upward nature of meandering stream deposits, but this is nowhere explicitly stated. For example:
"The modern deposits of vertical accretion usually lie
upon older deposits of similar origin, which in turn are
typically underlain by sandy channel deposits that were
accumulated when the channel occupied other positions
than at present These older channel sands may represent
lateral accretion on the inside of gradually shifting channel
bends, or they may represent fl.lling of former channels
abandoned by avulsions. More recent deposits of lateral
accretion, in generally crescentic shapes along the inside of
stream bends, may still be exposed at the surface but are
typically lower than the surface of the adjacent older floodplain which has been covered by deposits of vertical accretion."
Happ et al.' s ( 1940) work was descended from that
of Melton (1936; quoted earlier) and Mackin (1937),
who discussed lateral accretion in pebbly rivers and
illustrated diagrammatically the development of the
now-familiar lateral-accretion surfaces (Fig. 2.12).
This paper was incorporated into the geological literature on fa cies models by Allen (1964) but, apart
from this, it has rarely been referred to in the sedimentological literature. This is in marked contrast to
Fisk's (1944, 1947) work, which undoubtedly constitutes the most widely quoted source in alluvial sedimentology. Some Russian work (e.g., Shantzer 1951;
Botvinkina et al. 1954) rivals that of Fisk in its scope
but, being in Russian, it had little influence on the
Western "school" of sedimentology (again, except
for Allen's work).
Fisk's two classic reports (1944, 1947) contributed
a wealth of detail on the Mississippi fluvial and deltaic plain. The postglacial history of the Mississippi
was documented in detail, paleochannels were
mapped, the sediments were described, and the processes of fluvial sedimentation, including meander
migration and cutoff, and the fo rmation of day
plugs, levees, and splay deposits were all discussed in
detail. The reports were based on detailed fieldwork, 16000 boreholes, and examination of aerial
photos. They remain as one of the most detailed
studies of an alluvial system ever undertaken, and
this is the most valuable aspect of Fisk's contribution. Most of the main fluvial sedimentary processes
and products were fa irly well understood in a qualitative way by the 1940s, and Fisk fi lled out this knowledge with the necessary detailed documentation.
C c COLLWIAL OEPOSITS ALONG VALlEY SlOES
Vd • VERTICAL ACCRETION DEPOSITS
/.(!} • LATERAL ACCRETION 0EPOS1TS
.5 • SPLAYS ALONG fllLEO CHANNEL
k • TRENCHED TR!9UTARY VALLEY
p • CHANNEL FILL
t:) " ALL!JVIAL fANS
25
Fig. 2.11. A fluvial block-diagram model: "diagram illustrating typical relations of the various types of deposits in the
valley accumulation". (Happ et aL 1940)
the fi ning-upward nature of meandering stream deposits, but this is nowhere explicitly stated. For example:
"The modern deposits of vertical accretion usually lie
upon older deposits of similar origin, which in turn are
typically underlain by sandy channel deposits that were
accumulated when the channel occupied other positions
than at present These older channel sands may represent
lateral accretion on the inside of gradually shifting channel
bends, or they may represent fl.lling of former channels
abandoned by avulsions. More recent deposits of lateral
accretion, in generally crescentic shapes along the inside of
stream bends, may still be exposed at the surface but are
typically lower than the surface of the adjacent older floodplain which has been covered by deposits of vertical accretion."
Happ et al.' s ( 1940) work was descended from that
of Melton (1936; quoted earlier) and Mackin (1937),
who discussed lateral accretion in pebbly rivers and
illustrated diagrammatically the development of the
now-familiar lateral-accretion surfaces (Fig. 2.12).
This paper was incorporated into the geological literature on fa cies models by Allen (1964) but, apart
from this, it has rarely been referred to in the sedimentological literature. This is in marked contrast to
Fisk's (1944, 1947) work, which undoubtedly constitutes the most widely quoted source in alluvial sedimentology. Some Russian work (e.g., Shantzer 1951;
Botvinkina et al. 1954) rivals that of Fisk in its scope
but, being in Russian, it had little influence on the
Western "school" of sedimentology (again, except
for Allen's work).
Fisk's two classic reports (1944, 1947) contributed
a wealth of detail on the Mississippi fluvial and deltaic plain. The postglacial history of the Mississippi
was documented in detail, paleochannels were
mapped, the sediments were described, and the processes of fluvial sedimentation, including meander
migration and cutoff, and the fo rmation of day
plugs, levees, and splay deposits were all discussed in
detail. The reports were based on detailed fieldwork, 16000 boreholes, and examination of aerial
photos. They remain as one of the most detailed
studies of an alluvial system ever undertaken, and
this is the most valuable aspect of Fisk's contribution. Most of the main fluvial sedimentary processes
and products were fa irly well understood in a qualitative way by the 1940s, and Fisk fi lled out this knowledge with the necessary detailed documentation.