Mazon Creek - Fossil Ecosystems of North America: A Guide to the Sites and their Extraordinary Biotas - page 112

109

109 Death trail of undescribed
solemyid bivalve. The bivalve
was still alive and attempting to
escape while the siderite nodule
was forming, resulting in a
fossilized trail and the bivalve at
the edge of the nodule. CFM.
Scale bar is in cm.

110

110 Diagram showing the rapid
formation of a siderite nodule
around a dead shrimp. A, Dead
shrimp lands on sea floor; B, partial
decay by bacteria, volatiles rise;
C, siderite precipitation while
compaction begins; D, further
compaction of surrounding sediment
while dewatering syneresis causes
cracks to extend from centre of
nodule outwards after Baird et al.,
1986.

A

B

C

D

111

111 Section through the
Francis Creek Shale laminites
and part of a siderite nodule.
Note the laminae widen
towards the nodule, indicating
greater compaction of
the surrounding silt/clay
laminites than the nodule,
and that compaction had
started during growth of the
nodule. Thickest part of
specimen left is 1.6 in
4 cm.