342 
NATURE 
[August 12, 1886 ’ 
The species obtained were the following, my determin- 
ations in every case being indorsed by Messrs. Sharman 
and Newton :— 
Pyrula reticulata, Lam. | 
Nassa prismatica, Broc. | diluvit, Lam, 
Ringicula ventricosa, J. Sow. England) 
Pleurotoma turrifera (2), Nyst.| Leda, sp. (not ZL. myalis) 
consobrina (?), Bellaidi Mucula, sp. 
(Upper Miocene) Diplodonta rotundata, Mont., 
Fouannett (?), Des M. oval var. 
(Upper Miocene) Cardium, 3 sp. 
Trophon muricatus, Mont. Cardita sentlis, Lam. 
Cerithium tricinctum, Broc. Astarte Basteroti, Laj. 
Turritella incrassata,J. Sow. | ,, gracilis, Munster 
Fusus, sp. (= an undetermined Zafes, sp. 
Red Crag species) Gastrana fragilis, Linn. 
Scalaria clathratula, Turt. Tellina donacina, Linn. 
Margarita trochoidea (2), S. V.\ Mactra, sp. 
Wood, var. Lutraria elliptica, Lam. 
Trochus millegranus, Phil. Teredo (?) 
Natica, 2 sp. Terebratula grandis, Blum. 
Bulla Agnaria, Linn. Lunulites (?) 
Ostrea, sp. (young) | Balanus, sp. 
Pecten, 2 sp. Diadema (?) 
Pectunculus glycimeris, Linn. | 
Arca lactea, Linn. 
(new to 
” 
” 
The first thing that strikes one in this list is that the 
whole of the living species are southern forms, and the 
nearest allies of the extinct species belong to much 
warmer seas than ours. This, and the general character 
of the fauna, and proportion of extinct species, lead me 
to refer the beds to the Older Pliocene period, and to 
correlate the deposit with our Coralline Crag and with 
the Lower Crag or Diestian-of Belgium. The fossiliferous 
clay of St. Erth, in Cornwall, I also think is of about 
the same age, and not newer. 
Some curious questions are raised by these recent dis- 
coveries, and by others equally remarkable in Belgium 
and Holland. We now find that, instead of the Older 
Pliocene period being one of elevation, there must have 
been wide-spread submergence over great part of Western 
Europe. 
rally considered to be our only representative of the 
period, and as it did not rise much above the sea-level, it 
was often assumed that much of the rest of England was 
dry land. Now it is known that Pliocene beds cap the 
highest parts of the North Downs, and from the undis- 
turbed position of the shells, unworn, and generally with 
the valves united, it is evident that the depth of water 
must have been sufficient to prevent the deposits at the 
bottom being affected by storms. A subsidence sufficient 
to allow only 20 or 30 fathoms of water over the highest 
parts of the North Downs (and the depth in which the 
Lenham shells lived could hardly have been less) would 
submerge the whole of the east and south of England, 
except a few hills. : 
In Cornwall also there appears to have been a sub- 
mergence to a considerable depth, for the St. Erth clay 
was evidently laid down in still water, which would not 
be found at a less depth than 4o or 50 fathoms in a dis- 
trict exposed like this to the Atlantic swells. The fossils 
also in that clay point to some considerable depth of 
water, while the general flattened contour of the country 
suggests that this district has nearly all been submerged 
within a comparatively recent period. The lower parts 
of Cornwall form a smooth, undulating country, out of 
which rise abruptly the higher hills. Round one of these 
hills—St. Agnes Beacon—coarse sand is found at a high 
level. This is probably a beach deposit of the same age 
as the clay at St. Erth, though all fossils have now dis- 
appeared from it. Cornwall seems at that period to have 
formed a scattered archipelago like the Scilly Islands. 
Among the hard rocks of Cornwall denudation does not 
appear much to have changed the general configuration 
of the country since the Older Pliocene period. Moreover 
A few years since the Coralline Crag was gene- | 
| expect to find in the Coralline Crag the deposits and fauna 
the Phocene deposits were probably never continuous or 
thick, but merely formed patches in sheltered places and 
round the shores, the rest of the sea-bottom being rocky. 
In the south-east and east of England, however, the case 
was different, for the rocks of that region are soft and 
much more easily denuded. The position of the Lenham 
beds, at the very edge of an escarpment, over 600 feet 
above the sea, indicates that the great valleys of the 
Thames and Weald have to a large extent been excavated 
since Pliocene times. 
On the other hand, the question arises whether the 
elevation of the Wealden axis was still in progress during 
the Pliocene period. That the greater part of this 
enormous disturbance had been completed before that 
period seems proved by the absence of any Pliocene beds 
in the Hampshire or London basins in the synclinal folds 
parallel with the Weald. But there is possibly evidence 
of less violent movements of upheaval in the different 
levels at which Older Pliocene beds now occur. We find 
the Coralline Crag slightly above the present sea-level, 
the Lenham beds 610 feet above, while at Utrecht ‘ 
deposits of about the same age are found at a depth 
of at least 1140 feet below the sea, and their bottom 
has not yet been reached.! If the movements in North- 
Western Europe have been regular and of equal amount 
everywhere, then, taking the Downs near Lenham as the 
starting-point, with a depth of 20 fathoms, we should — 
of 120 fathoms, and at the bottom of the well at Utrecht _ 
those of 310 fathoms. ‘ 
A Pliocene fauna of over 300 fathoms would be most 
interesting to examine, but of such a fauna no trace has 
yet been detected anywhere in North-Western Europe. 
The Pliocene deposits, though now at such different levels, 
are shown by their included fossils to have been laid down 
in about the same depth of water. Though differing 
much in mineral composition at the various localities, 
they nevertheless agree as closely in regard to their shells 
as the very different nature of the sea-bottoms would lead 
us to expect. The whole 1143 feet of Pliocene and Pleis- — 
tocene beds at Utrecht consists of essentially shallow- 
water deposits, pointing to a continuous depression. 
Were we to assume that the present positions of the 
Pliocene deposits of the north-west of Europe represent 
the relative depths at which the beds were originally laid 
down, a curious difficulty would present itself in any attempt 
to compare the Pliocene and recent sea-bottoms. Anydeep 
depressions in the seas around England are now filled 
with cold water and contain an Arctic fauna. In similar 
depths during the Pliocene period one would expect to find 
a similar fauna, unless there existed, as in the Mediterra- 
nean, a barrier to cut off the Polar currents, or unless 
there was at that time no cold area at the Pole. Neither 
of these explanations seems sufficient, and it is more 
probable that those geologists are right who maintain 
that the direction of the movements in areas of sub- 
sidence or elevation remains the same during long periods. 
Holland may thus have undergone continued, though 
probably intermittent, depression since the early part of 
the Pliocene period ; thus allowing the accumulation of 
a great thickness of shallow-water Newer Tertiary beds. 
The axis of the Weald, including the Downs near Len- 
ham, has been correspondingly elevated. Suffolk was 
little affected, and the deposits were therefore, in that 
district, thin and largely of organic origin. : 
I do not bring forward these conclusions as to elevation 
and submergence as indisputable facts, but merely as the 
results of my recent studies in the Pliocene beds at home 
and on the Continent. Any day new discoveries may 
profoundly modify our views, but the curious facts will 
remain, that Northern Europe has yielded only a shallow- | 
water Pliocene fauna, and no trace of boreal outliers such — 
* See Dr. J. Lorié, “ Contributions 2x la Géologie des Pays-Bas,’ 
Archives du Musée Teyler, ser. ii. vol. ii. part 3. 
5 
