Arkell.1956.Jurassic..

150 THE ALPS AND NORTHERN CARPATHIANS
shales, poor in ammonites (Haug, 1891, p. 82), resting on richly fossiliferous
marly limestones which are at latest Lower Bathonian in the north but
rise progressively southwards until they include a horizon with Wagnericeras
wagneri and Bullatimorphites which, if correctly identified, indicate
the Aspidoides Zone (early Upper Bathonian); in other words, the
Posidonia shales thicken northwards, away from the Esterel massif and
towards the Alpine geosyncline, and engulf progressively earlier zones
(Guillaume, 1938). Similar lateral changes of facies occur in the Dept.
of Var (Parent, 1938).
An Upper Bathonian fauna with Clydoniceras discus, Choffatia
subbakeriae, Siemiradzkia aurigera, Spiroceras sp., Epistrenoceras subcontrarium
(Behr.) (see R. Douville, 1915, 'Etudes sur les Cosmoceratidae',
pi. vii, figs. 10-25) and some 50 species of other mollusca, brachiopods,
etc., is developed in marl layers among sands and sandy limestones in
Provence (Dept. of Var), where the Bathonian is about 150 m. thick
(Parent, 1935, 1940; see also Parent, 1933, 1940a).
The existence of other Upper and Middle Bathonian faunas in Provence
is indicated by Lanquine (1929, pp. 315-22) who records Prohecticoceras
retrocostatum (de Gross.), P. haugi (Popovici), Schwandorfia lanquinei
Arkell (Lanquine, p. 316, pi. xi, fig. 5); and 'Pachyceras' sp. recorded by
Haug (1891, p. 80) probably refers to a Morrisiceras or Lycetticeras as in
other parts of Europe.
The Lower Bathonian is strongly represented with a long list of
characteristic ammonites of the Zigzag Zone perhaps unequalled anywhere
in the world; for it combines the extra-Alpine fauna with masses
of Phylloceratids and also Lytoceras adeloides Kud. and Nannolytoceras
tripartitum (Rasp.), as in Algeria and Sicily, but seems to be easier for the
collector. Besides the usual Zigzagiceras, Procerites, Morphoceras,
Ebrayiceras, Parkinsonia, Oecotraustes, Oxycerites, Cadomites, etc., there
are some particularly interesting items, such as a form recorded by both
Haug (1891, p. 79) and Parent (1938) as Strigoceras cf. truellei (d'Orb.),
also Bullatimorphites (ymir Oppel ?) a genus usually not found before
the Middle or Upper Bathonian, and Garantiana bathonica Lissajous.
(Haug, 1891, p. 79; Lanquine, 1929, p. 315; Parent, 1938).
BAJOCIAN
About Digne the Bajocian is at least 200 m. thick and consists mainly
of compact or marly limestones with marly or shaly partings, poor in
fossils excepting cephalopods, Posidonia, Inoceramus and Cancellophycus,
which abound at certain levels. There is an imperceptible passage upwards
into the Bathonian and downwards into the Toarcian, the Opalinum
Zone being developed as black clays indistinguishable from the Lias.
In the Alpes Maritimes the Bajocian is represented mainly by dolomites,
cherty limestones and oolites, with a varied fauna of pelecypods, gastropods,
brachiopods, echinoids and corals, but no ammonites. In Provence
the facies is also neritic but more variable and the mixed fauna of
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