22
1960s. Various workers experimented with the production of cross-bedding (McKee 1957; Brush 1958;
Jopling 1963, 1965), but the most important developments were those of Simons and Richardson (1961),
in which the flow-regime concept was established.
This work later appeared (with C.F.. Nordin as an
additional co-author) in a collection of papers on the
hydrodynamics of primary sedimentary strucures
edited by Middleton (1965). Much of the work of
earlier years on fluid mech;:mics and sediment transport was brought to bear on sedimentological problems in this book. The statement of the flow-regime
concept and demonstrations in the fi eld and the
flume of the relationship between bedforms and
sedimentary structures were the two principal features of the book, and it had a major influence on
sedimentologists over the next decade. The development of ideas on the hydraulic interpretation ·of
sedimentary structures up to the mid-1970s was described in detail by Middleton ( 1977).
Parallel to the North American work, mentioned
above, was that of Allen, who reviewed much engineering work on bedforms and carried out his own
flume experiments on the flow patterns associated
with the various ripple types. Most of this work is
contained in his books (Allen 1968, 1970a, 1984).
One of the most widely used parts of this work was
the diagram showing the control of flow velocity and
sediment grain size on the stability of the principal
bedforms.
Descriptive papers on bedforms and bars in modern sandy rivers published prior to the First International Symposium on Fluvial Sedimentology (held
in Calgary in 1977) include those of Carey and Keller
(1957), Harms et al. (1963), Harms and Fahnestock
(1965), Coleman (1969), Collinson (1970), N.D.
Smith (1970, 1971), Williams (1971), and jackson
(1976a). All provided much useful data regarding
morphology and internal structures; orientation
measurements were provided by some, and most of
these papers have been widely used in interpretations of the ancient record.
Paleocurrent variance in alluvial systems has
been discussed by a fe w workers. Potter and
Pettijohn (1977, p. 108-!11) summarized the early
research in this area. An important concept was
introduced by Allen (1966, 1967), who classifi ed
sedimentary structures into a hierarchy of sizes and
attempted to relate this to the variability shown by
paleocurrent measurements. Miall (1974, 1976) developed these ideas fu rther (Fig. 2.10). Collinson
(197la) and Schwartz (1978) showed how paleocurrent dispersion varies with discharge. Jackson
Historical Background
(1975) showed the time-dependent nature of the elements in the bedform hierarchy, and Allen (1973,
1974a) discussed the problems associated with
bedform lag - their slowness to respond to changes
in flow conditions and the implications for hydraulic
interpretation (the concept of lag had been introduced by Kennedy 1963). Southard (1971) and
Harms et a!. (1975, 1982) demonstrated the importance of a third parameter, depth 1 in controlling
bedform morphology, and the recognition of this
important point has allowed a much greater degree
of precision in the prediction of bedform morphology fr om flow conditions. Harms et a!. (1975) also
recorded the recognition of a new '
ripple and dune phase. Such fe atures had been first
recognized in experiments by French workers in
1963, and were subsequently recorded in the natural
state in intertidal environments (see Middleton
1977).
Pebbly rivers were studied by Johansson (1963),
Williams and Rust (1969), Rust (1975), N.D. Smith
(1974), and Gustavson (1974, 1978). Measurement
and interpretation of clast imbrication have been an
important part of this work. Hein and Walker (1977)
proposed a model for the evolution of bars in gravel
rivers, and Shaw and Kellerhals (1977) and Koster
(1978) discussed the interpretation of antidunes in
fl uvial gravels.
2.3.6 Fluvial Facies Models
2.3.6. 1 From Hobbs to Fisk
In 1917, Grabau wrote:
"From the very first, students of sediments have been in
the main, marinists, though when the organic evidence
pointed unmistakably to the presence of fresh waters they
resorted to a lacustrine variant. Even today the interpretation of sediments as of other than marine or lacustrine
origin meets with a good deal of skepticism in some circles,
and the fluviatilists are not much in favour, especially
when they intrude upon territory hitherto preemptied by
the marinists ... Fortunately however, American geologists
are the most tolerant of men, and even the most startling
idea gets a hearing if they are supported by fact and are the
result of logical reasoning.,
Some of the early attempts at fluvial interpretation have been quoted earlier in this section. That by
Medlicott and Blanford (1879) was well ahead of its
time, probably because exposures of the Siwalik
sediments are located close to the great rivers of the
Indo-Gangetic plain - an inescapable modern ana-
1960s. Various workers experimented with the production of cross-bedding (McKee 1957; Brush 1958;
Jopling 1963, 1965), but the most important developments were those of Simons and Richardson (1961),
in which the flow-regime concept was established.
This work later appeared (with C.F.. Nordin as an
additional co-author) in a collection of papers on the
hydrodynamics of primary sedimentary strucures
edited by Middleton (1965). Much of the work of
earlier years on fluid mech;:mics and sediment transport was brought to bear on sedimentological problems in this book. The statement of the flow-regime
concept and demonstrations in the fi eld and the
flume of the relationship between bedforms and
sedimentary structures were the two principal features of the book, and it had a major influence on
sedimentologists over the next decade. The development of ideas on the hydraulic interpretation ·of
sedimentary structures up to the mid-1970s was described in detail by Middleton ( 1977).
Parallel to the North American work, mentioned
above, was that of Allen, who reviewed much engineering work on bedforms and carried out his own
flume experiments on the flow patterns associated
with the various ripple types. Most of this work is
contained in his books (Allen 1968, 1970a, 1984).
One of the most widely used parts of this work was
the diagram showing the control of flow velocity and
sediment grain size on the stability of the principal
bedforms.
Descriptive papers on bedforms and bars in modern sandy rivers published prior to the First International Symposium on Fluvial Sedimentology (held
in Calgary in 1977) include those of Carey and Keller
(1957), Harms et al. (1963), Harms and Fahnestock
(1965), Coleman (1969), Collinson (1970), N.D.
Smith (1970, 1971), Williams (1971), and jackson
(1976a). All provided much useful data regarding
morphology and internal structures; orientation
measurements were provided by some, and most of
these papers have been widely used in interpretations of the ancient record.
Paleocurrent variance in alluvial systems has
been discussed by a fe w workers. Potter and
Pettijohn (1977, p. 108-!11) summarized the early
research in this area. An important concept was
introduced by Allen (1966, 1967), who classifi ed
sedimentary structures into a hierarchy of sizes and
attempted to relate this to the variability shown by
paleocurrent measurements. Miall (1974, 1976) developed these ideas fu rther (Fig. 2.10). Collinson
(197la) and Schwartz (1978) showed how paleocurrent dispersion varies with discharge. Jackson
Historical Background
(1975) showed the time-dependent nature of the elements in the bedform hierarchy, and Allen (1973,
1974a) discussed the problems associated with
bedform lag - their slowness to respond to changes
in flow conditions and the implications for hydraulic
interpretation (the concept of lag had been introduced by Kennedy 1963). Southard (1971) and
Harms et a!. (1975, 1982) demonstrated the importance of a third parameter, depth 1 in controlling
bedform morphology, and the recognition of this
important point has allowed a much greater degree
of precision in the prediction of bedform morphology fr om flow conditions. Harms et a!. (1975) also
recorded the recognition of a new '
ripple and dune phase. Such fe atures had been first
recognized in experiments by French workers in
1963, and were subsequently recorded in the natural
state in intertidal environments (see Middleton
1977).
Pebbly rivers were studied by Johansson (1963),
Williams and Rust (1969), Rust (1975), N.D. Smith
(1974), and Gustavson (1974, 1978). Measurement
and interpretation of clast imbrication have been an
important part of this work. Hein and Walker (1977)
proposed a model for the evolution of bars in gravel
rivers, and Shaw and Kellerhals (1977) and Koster
(1978) discussed the interpretation of antidunes in
fl uvial gravels.
2.3.6 Fluvial Facies Models
2.3.6. 1 From Hobbs to Fisk
In 1917, Grabau wrote:
"From the very first, students of sediments have been in
the main, marinists, though when the organic evidence
pointed unmistakably to the presence of fresh waters they
resorted to a lacustrine variant. Even today the interpretation of sediments as of other than marine or lacustrine
origin meets with a good deal of skepticism in some circles,
and the fluviatilists are not much in favour, especially
when they intrude upon territory hitherto preemptied by
the marinists ... Fortunately however, American geologists
are the most tolerant of men, and even the most startling
idea gets a hearing if they are supported by fact and are the
result of logical reasoning.,
Some of the early attempts at fluvial interpretation have been quoted earlier in this section. That by
Medlicott and Blanford (1879) was well ahead of its
time, probably because exposures of the Siwalik
sediments are located close to the great rivers of the
Indo-Gangetic plain - an inescapable modern ana-