189 
1916-17.] The Hurlet Sequence and the Abden Fauna. 
branaceus, Spirorbis caperatus , Dithyrocaris glabra, D. granulata, D. 
ovalis, D. testudinea, D. tricornis, Discina nitida, Lingula squamiformis, 
Productus semireticulatus, P. longispinus , Rhynchonella pleurodon, 
Streptorhynchus crenistria, Aviculopecten knockonniensis , Posidonomya 
corrugata, Nuculana attenuata, Protoschizodus cequilateralis, Nucula 
gibbosa, Sanguinolites plicatus , Orthoceras attenuatum, Nautilus sp. 
Still further upstream, and on its left bank, is the escarpment known 
as the Black Craig, which shows a thick series of alternating hands of 
ironstone and shale. In the shale near the foot of the cliff* is a bed rich 
in Lingula squamiformis and Productus, which marks the position of the 
Top Marine Band. 
The next section we describe is that shown in the neighbourhood of 
Carluke. When the original survey of the Carluke district was made 
in 1873 the whole area was being opened up by mines and opencast 
workings, and at that time it was much more easy to study the group 
of strata under consideration than it is now, as many of the sections are 
not now exposed. The records that have been left are, however, particularly 
full and clear, especially those of Dr Rankine and Dr Hunter, and there 
can, we think, be little dubiety in correlating the limestones of the Carluke 
district with those of the Hurlet district and the West of Scotland generally.* 
It is not considered necessary to here discuss in detail the stratigraphical 
and palaeontological evidence upon which the correlation is based, as 
that has already been done in a paper published in the Transactions of 
the Geological Society of Glasgow. The following table shows the princi- 
pal horizons in the Hurlet district and their equivalents in the Carluke 
district : — 
Hurlet District. 
Carluke District. 
Lingula Shale and Top Marine Band 
Johnstone C.B. Ironstone. 
Slingstone Limestone. 
Calderwood Cement 
Lillies Coal and Ironstone. 
Lingula Limestone. 
Main Hosie Limestone . 
Birkfield Limestone. 
Hosie Sandstone . 
Raesgill Ironstones. 
Blackhall Limestone 
Foul Hosie Limestone. 
Househill Ironstones 
Selkirk Ironstones. 
Hurlet Limestone ... 
Second Calmy Limestone. 
Alum Shale ..... 
Fossiliferous Blaes. f 
* Trans . Geol. Soc. Glasgow , vol. xv, p. 404. 
t At Thorn, 1 J miles north-east of Carluke, the second Calmy Limestone is underlain by a 
fossiliferous blaes containing a varied fauna, with numerous shells of Sanguinolites costellatus. 
This we regard as the equivalent of the Hurlet Alum Shale fauna. 
