|
Bivalve
fossils are not as common and not as diverse as gastropods. They are
most often found as pyrite casts in the accumulations on the beach.
The shell is usually missing. This is due to wave action. However when
fresh slips occur they can be found with their original shell still
largely intact. Very occasionally they are preserved on phosphatic nodules
or on or in septarian cement stones. Unless the shell is infilled with
a substance that helps to retain the calcium content of the shell they
do not preserve well. So the shell needs to be associated with pyrite,
phosphatic material or cement stone to stand any chance of consolidated
preservation. If the shell is not in contact with these substances it
is often decalcified in the clay. If this is the case then on contact
to a drying atmosphere the shell soon crumbles away.
|
 |
 |
|
|
Astarte
filgera
|
Astarte
rugata
|
|
 |
 |
|
|
Astarte
sp
|
Astarte
sp.
|
|
 |
 |
|
|
Striarca
wrigleyi
|
Abra
splendens
|
|
 |
 |
|
|
Cuspida
inflata
|
Ledina
amygdaloides
|
|
  |
||