(Quarterly Geological
Journal volume 20 page 97 1864.) This being the case, we might fairly expect
that if we had a marine equivalent of the Bembridge series or of the
contemporaneous Paris gypsum, we should find it to contain a still greater
number of shells common to the Tongrian beds of Belgium, but the exact
correlation of these fresh-water groups of France, Belgium, and Britain has not
yet been fully made out. It is possible that the Tongrian of Dumont may be newer
than the Bembridge series, and therefore referable to the Lower Miocene. If ever
the whole series should be complete, we must be prepared to find the marine
equivalent of the Bembridge beds, or the uppermost Eocene, passing by
imperceptible shades into the inferior beds of the overlying Miocene strata.
Among the fossils found in the Middle Headon are Cytherea incrassata and
Cerithium plicatum (Figure 160 Chapter 15). These shells, especially the latter,
are very characteristic of the Lower Miocene, and their occurrence in the Headon
series has been cited as an objection to the line proposed to be drawn between
Miocene and Eocene.
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