PROCEEDINGS OF GEOLOGICAL SOCIETIES, 
553 
east, and appears to be found again at High Papwortli, v. csi of Elswoitli. As 
the St. Ives rock dips to the east, so will the Elsworth rock also, and therefore 
the clay to the east and south will be superior to it, while that to the west is 
inferior. Passing then west to St. Xeots, auotiier rock occurs, and this would 
seem to be very low down in the series, and uot far removed from the zone of 
the KellowBV rock. The St. Neots rock consists of thin layers of limestone, 
which are alternate with thin beds of clay. 
Among the fossils in the Oxford Clay, at St. Xeots, are Anirnonites Diaicanii, 
A. spiiiosus, A. afhletliKs, A. coronatus, &c. The commoner forms at St. Ives 
are Amhioiiites Mar'ue, A. cordate^, A. Eii.fjenii, As GoUatlii'.s, &c., &:q. Of the 
Ammonites in tlic clay above the St. Ives rock, uo good list is known, but 
among them are A. alfeniai/.'s, and A. baheani'is. ]3oth at Elsworth and Blun- 
tislian), above the rock, the Gri/pluea dilatafa is found abundantly, aud oc- 
casionally with it Ostivea deltoidea ; but to the south the latter fossil is more 
abundant, so tliat at Tetworth the specimens occur in equal profusion, and in 
combination with Ammo/iites Achilles, Beleiiuntes eccentric us, Lima pectiuiformis, 
Seqnda tetragoiut, &c., &c. At Tetworth there is a thin band of rock, as there 
is also at Gamlingay ; at Box worth, nearly, if not in the same position, there 
is a rook of the same thickness; and to the east, beyond this the clay seems 
to graduate imperceptibly up to the Ximmcridge clay of Cottenham. 
There is thus a great thickness of strata between the Oxford and Kim- 
meridge clays, in which the fossils of both tiiose deposits arc intermixed, and 
which represents the Coral-rag. Tluit such a clay did exist might have been 
inferred from the presence of the Coral-rag at Upwarc, aud its limited exten- 
sion beyond. The Upware limestone was a coral-reef out in an old sea, and it 
must have necessarily happened that beyond the narrow limits of the reef a 
deposit of a ditferent kind would have been formmg on the sea-bottom, far more 
widely spread than the liuicstone. This formation is named the Tetworth clay.''^" 
A ditticult question then arose as to the limits of the clay, for if it were re- 
placed by Coral-rag, it would result that the Elsworth rock would be immedi- 
ately beneath the Coral-rag on the one hand, and above the Oxford clay on the 
other, and so would appear to be rather a member of the former series than of 
the latter. However, the presence of such forms as Belemnites tornatilis, 
B. hastattis, Ammoi/itets vertebralis, A. biplex, A. perarmatus, A. Henrici, A. 
GUiialiculatKs, A. goliathus, &c., were held as conclusive evidence that it ought 
rather to be regarded as the u|)permost zone of Oxford clay. The upper 
boundary of the Tetworth clay cannot be given with any certainty. Aud from 
the want of sections it has not been found possible to subdivide the strata 
above, as has been done below. 
Such is the Eoi-clay. The rocks of its lower part do not appear to occur in 
the south of England, though there are divisions of the clay corresponding to 
those so strongly marked by their occurrence here. The Tetworth clay has 
long been known to have an extensive southern development ; a portion of it 
appears to have been mapped by the Geological survey as Oxford clay, just as 
iji one district Mr. Lucas Barrett mapped it with the Kimmeridge clay. 
The autlior concluded by expressing his indebtedness, for mueh kind as- 
sistance, to the Kev. S. Banks, of Cottenham, the Rev. H. Uobson, of Els- 
worth, to Mr. J. Carter, of Cambridge, and to Mr. J. J. Evans, of St. Neots. 
Malvern Naturalists' Eield Club. — The last meeting of this dis- 
tinguished club of observers of nature in the lields of research, was held at 
XJpton-on-Severn. 
The chief feature in the operations of the day was the examination of the 
♦ At the Manchester meeting of the British Association, the name of Bluntisham clay wag 
suggested for it, but as the section there is no longer visible, it has been tliought bettei- to 
name it from a locaUty where it may be seen and worked. 
VOL. IV. O Q 
