A model is developed to explain the wide range of sedimentary structur
es found in ancient storm-deposited beds, The model predicts the natur
e and association of internal sedimentary structures and sole marks th
at correspond to various storm flow conditions. Despite recent studies
that reveal the signature of ancient storms with geostrophic flow sys
tems like those documented from the modern, nonactualistic storm proce
sses are needed to explain the unusual thickness and wider cross-shelf
distribution of ancient tempestites. Mechanisms for storm transport o
f sediment onto the shelf are best recorded in sole marks, which appea
r to show a range of predepositional conditions from purely oscillator
y flow to combined how to purely unidirectional flow, The depositional
phase of tempestites is also highly variable both from bed to bed and
from basin to basin, as reflected in the wide range of vertical strat
ification sequences in the ancient. Most recent authors have considere
d excess-weight (density induced) forces to have been relatively unimp
ortant in ancient storm deposition, This view results from a major lea
p in understanding of modern storm processes, particularly the dynamic
s of combined-how bottom boundary layers, during the last 15 years, It
also comes from the unsubstantiated view that because the bottom slop
es and measured storm-generated near-bottom sediment concentrations of
modern shelves are presumably too low for autosuspension, such forces
are unimportant, Experiments on the interaction of waves and density
flows define the conditions under which mixing forces destroy density
stratification, and also raise the possibility that with high Richards
on numbers, wave-generated shear stresses may enhance turbulence just
enough to raise sediment concentrations in the boundary layer and thus
facilitate transport by excess-weight forces, We also believe that ex
cess-weight forces are potentially important for the following reasons
: (1) sediment concentrations during peak storms conditions exceed 100
0 mg/l on inner shelves, and may therefore be nonnegligible and import
ant for cross-shelf transport with or without currents and waves; (2)
one cannot rule out catastrophic introduction of sediment by river flo
ods, earthquakes, or other events that caused liquefaction during anci
ent storm events, particularly given the significant difference in max
imum thickness between ancient and modern storm generated beds; (3) th
e slopes of modern continental shelves may be anomalously low as a res
ult of Holocene sea level rise, and therefore poor analogs for many an
cient storm-influenced settings. Higher slopes may have been the norm
in a wide variety of ancient tectonic settings, thus providing greater
offshore-directed driving force for sediment-rich, storm-generated su
spensions.