A. J. Juices Browne — On the Upper Greensand, etc. 359 
De. Baerois’ Classification. 
Having now reviewed the various descriptions and definitions 
which have been given of the Upper Greensand and Chloritic 
Marl up to the year 1875, I proceed to notice those given in the 
recently published researches of Dr. Ch. Barrois, 1 which have, I 
conceive, gone far towards harmonizing the conflicting opinions 
previously existing with regard to the Constitution and im- 
portance of these beds, and towards establishing a more natural 
method of grouping the strata in this portion of the Cretaceous 
series. 
In this work Dr. Barrois has shown that a proper understanding 
of the Cretaceous System (as of all other Systems) can only be 
attained by one who unites the qualifications of a palseontologist 
with those of a field-geologist ; and no one, I think, can study the 
pages of his “ Recherches ” without admitting that he himself pos- 
sesses these qualifications in an eminent degree. 
He has also reminded us, or rather takes for granted that we 
remember what some of us seem apt to forget, that lithological 
characters alone form untrustworthy foundation for rock-groups, 
that the same stage or formation can be a clay in one district and 
a marl or sandstone in another, that Gault may include sand as 
well as clay, and that tbis is particularly the case with the Upper 
Gault or zone of Ammonites inßcitus. 
Working on these data he has determined the existence of a succes- 
sion of palgeontological zones from the Gault upwards througliout the 
Chalk, and carefully followed them over the Cretaceous areas of the 
British Isles. 
The first four of these zones are as follows : — 
1. Zone of Amm. inflatus = Blackdown Beds. 
2. „ Pecten asper = Wanninster Beds. 
3. Chloritic Marl. 
4. Zone of Holaster subglobosm — Chalk Marl. 
Regarding the first two of these divisions, he says (p. 71), “The 
Upper Greensand, as defined by Berger, Inglefield, Webster, Fitton, 
and Ibbetson, appears to me every where divisible into two zones ; 
the zone of Am. inflatus, and the zone of P. asper. The fauna of 
the Upper Greensand, being a mixture of these two faunas, had of 
necessity relations with both.” Again at p. 105, “ I had thought 
that the lithological characters of the Upper Greensand would make 
it a special division, distinct from the other horizons ; but I was 
deceived, and in the Upper Greensand of the Isle of Wight, as in 
that of the rest of England, there are two perfectly distinct faunas, 
that of Blackdown and that of Warminster.” The case, however, is 
not quite so simple as would appear from this, for the lower and 
clayey portions of the Amm. inflatus zone have always been ex- 
cluded from the Upper Greensand ; the two zones therefore do 
not exactly form its equivalent, since they include more than the 
Upper Greensand. 
1 Recherches sur le Terrain Crdtacd superieur de l’Angleterre et de l’Ireland, par 
Ch. Barrois, D.Sc. Lille, 1876. 
