382 
to suppose that the channel which lay between this shore and 
the Mendips was quite free during Liassic time, because of the 
similarity of that Ammonite-fauna over England; but towards 
the close of the Lias, I presume that the same or a similar up- 
heaval to that which connected the Mendips with May Hill, joined 
the Mendips with the eastern coast. This is the relative position 
of land and water which I have indicated in the sketch-map 
attached ; and it will be seen that the Cotteswold sea is thereby 
cut off from all southward connection with the Dorset-Somerset 
sea, which is exactly what we might suppose from the difference 
in their Ammonite- and Brachiopod-faunas. 
The outward connection between the Cotteswold sea and 
the ocean must have been by way of the Cheshire Plain; and, 
possibly, for Mollusca to pass from the Dorset-Somerset area to 
the Cotteswold area, may have been a journey of some thou- 
sands of miles. If so, this barrier which I have supposed to 
have been erected by an extension of the Mendip axis, would 
be similar to the Isthmus of Suez. 
Possibly the result of these upheavals was to lessen the 
depth of sea over the Cotteswold area, and especially in prox- 
imity to the new shore;* but a kind of trough I imagine to 
have been formed from Haresfield to Wotton-under-Edge, and 
that this trough received a large deposit of sandy sediment 
derived from a new source which the upheaval had exposed to 
the action of the sea. This sandy sediment is what we know 
as Cotteswold Sands, and it is curious to notice that, after 
attaining a depth of nearly 150 feet in the Haresfield-Wotton 
district, it was succeeded by a marly-limestone period known as 
the Cephalopoda-bed. However, during the deposition of this 
Cephalopoda-bed, the yellow sandy sediment was accumulating 
in the neighbourhood of Bath—the Midford Sands being of later 
age than the Cotteswold Sands, but contemporaneous with part 
of the Cotteswold Cephalopoda-bed. 
* Jukes-Brown gives reasons why the Oolitic sea-floor was more elevated 
than in Liassic times: Building of the British Isles, page 152, 1888. These 
notes, however, were written some months before the appearance of that work. 
