Environmental Engineering Reference
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Wavy
Even
Discontinuous
Discontinuous
parallel
Wavy
parallel
Wavy
nonparallel
Curved
parallel
Parallel
Nonparallel
Parallel
Curved
nonparallel
Upward
gradation
Downward
gradation
Brecciated
Mottled
Structureless
Algal
FIGURE 2.25
Stratification types in fine-grained sediments.
(a)
(b)
FIGURE 2.26
Planar tabular (a) and trough or festoon (b) cross-bedding.
Structureless bedding represents rapid sedimentation with little or no change or variation in
the source material. Figure 2.25 shows many types of stratification in fine-grained sediments.
Cross-bedding are sets of bedded sediments at various, on-lapping, and inclined angles.
Cross-bedding indicates changing directions and perhaps energy in the direction of ori-
gin of the sediments being deposited. In sedimentary deposits, cross-bedding typically
indicates the deposit in question was affected by the forces of wind or changing water
currents. Cross-bedding occurs most often within coarse-grained sediments such as sand.
Figure 2.26 is a diagram showing the concept of cross-bedding (a is planar tabular and b is
trough or festoon cross-bedding). Figure 2.27 is a photograph of a sand deposit exhibiting
a festoon type of cross-bedding, and Figure 2.28 is a photograph of a sand deposit exhibit-
ing a planar tabular type of cross-bedding.
2.4.3 Other Depositional Features
Other depositional features may include remnants or identification marks useful for
identifying the environment and method creating the deposit. In addition to bedded and
stratified features, these other depositional features provide significant clues to geologists
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