282 ODLING : CORRELATION OF THE UPPER AND MIDDLE OOLITES 
On crossing the Channel to Boulogne, a very complete series of 
rocks from the Cornbrash into the Wealden may be examined in the 
coastal sections. Here the facies is for the most part argillaceous, 
except in the Corallian facies which is purely local. The limestones 
appear to be always argillaceous. Sandstones occur intercalated with 
the argillaceous deposits, and are for the most part neither constant 
over any large area nor restricted to definite horizons, as is the case 
with the Calcareous Grits and Portland Sands of this country. 
The most noticeable stratigraphical break in the series occurs 
about the centre of the Portlandien Inferieur with the Trigonia jiellati 
Conglomerate, which is certainly below the uppermost beds of our 
English Kimeridge Clay.* 
The lower beds of the Astartien, with possibly the upper part of 
the Argovien, may be roughly paralleled with the British Supra- 
Corallian, to which series they bear certain affinities. The conditions, 
however, under which they were deposited were apparently more 
Kimeridgean. 
The limestones composed almost entirely of Exogyra virgula form 
the most noticeable feature in the whole series. It is significant that 
this fossil flashes into prominence (in the zones of Ammonites orthoceras 
and A. calentanum) and then suddenly dies out, as in this country. 
The Pterocera oceani fauna appears to be unrepresented in Britain. 
The true Portland Series include a Hartwell Clay facies, and an 
Upper Portland facies somewhat resembling that in the Oxford District 
capped by similar Purbeck Beds. 
The resemblance between the two districts is further accentuated 
by the capping of ferruginous sands of Wealden age of a similar type 
to the Shotover Iron Sands. The complete sequence will be foimd 
by reference to Plate XXIX. 
Summary. 
The whole of the Middle and Upper Oolites form one natural group 
normally without any sharp break between the various members. 
* T. pellati is often recorded from the Portland of this country ; if 
this is identical with French species we have a further case of the same 
fossil occurring at different horizons in different areas. 
