Environmental Engineering Reference
In-Depth Information
FIGURE 4
Burrowing bivalves and the resultant traces. White scale bar is 2 cm. (A) Downward-
deflected sediment lamination (equilibrichnia; outlined by the white dashed line) around the bivalve
Tresus nuttalli
. (B)
Lockeia
(L) on a bedding plane, generated by
Mya arenaria
in mud. Bottle cap is
2.6 cm. (C) Concentric sediment lamination (dashed white line) around the siphon hole of
M
.
are-
naria
in sandy mud. Scale bar is in centimeters. (D) Single-siphon
Siphonichnus
(Si) made by
M
.
arenaria
in sand. Note the downward-deflected mud laminae around the siphon shaft. (E)
Dual-siphon
Siphonichnus
made by
Nuttallia obscurata
in sand. (F) Sand-filled
Gastrochaenolites
(Ga) made by
Petricola pholadiformis
(inset photo) in sandstone.
of
en-echelon
chevrons where the shell was pushed apart to drive the animal
forward. The movement of shallowly burrowing bivalves and gastropods can
cause significant disruption in the upper few centimeters of the sediment.
2.3 Crustaceans
The range of burrow morphologies produced by crustaceans rivals that of
vermiform animals. Crustacean burrows can be unlined or lined with fecal
material. Unlike vermiform animals, however, crustacean-burrow diameters
are commonly variable along their length. In marine settings, the dominant
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