187 
1916-17.] The Hurlet Sequence and the Abden Fauna. 
features as we have seen it possess at Blackhall in the Hurlet district, and 
it is overlaid by a highly fossiliferous blaes, No. 19 in the table, yielding 
the same fauna as was found by Dr Young in the pit on the South Hill, 
Campsie, and which has now been proved to form a well-marked horizon 
in the Lower Limestone Series of the West of Scotland. 
After passing over 150 feet of shales and sandstones we reach the Main 
Hosie Limestone, No. 12. This limestone is 2 feet in thickness, and passes 
upwards into the limey shales, carrying a rich marine fauna. 
The next calcareous horizon in ascending order is the Top Hosie or 
Calderwood Cement, No. 25 in table, which is well seen in relation to the 
underlying Main Hosie in stream No. 4, but is much better developed in 
stream No. 1, where it exhibits a striking similarity in appearance to the 
exposure in the type locality at Calderwood Glen. 
In stream section No. 1 the sandstones with Spiropliyton caudi-galli 
can be seen, but there is no exposure of the Top Marine Limestone, which 
is best seen about a mile and a half to the west in the Spouthead Burn, 
immediately to the south of the great fault. 
VI. Sections between Hurlet and Cobbinshaw. 
Having traced the Hurlet succession north-eastwards along the Campsie 
Hills, and, as we think, satisfactorily established the identity of the 
various fossiliferous horizons, we now proceed to consider the sections that 
lie between Hurlet and Cobbinshaw. There are numerous exposures along 
this line from west to east, but we shall only refer to those seen at 
Thorntonhall, Calderwood Glen, and that seen in the neighbourhood of 
Carluke. 
At Thorntonhall and the Kittoch Water the Blackbyre and Hurlet 
Limestones with the intervening strata are well shown, though at this 
point the Alum Shale is thin, and the fauna has not yet been found. 
The Blackhall Limestone with its overlying fauna is well shown in the 
Kittoch Water a little above Arrotshole. Entering Calderwood Glen at 
Crossbasket Bridge, 2 miles east of East Kilbride, a series of sandstones are 
exposed in the bed of the stream, which further down are seen to rest 
upon volcanic detritus and lavas. Further upstream the sandstones are 
succeeded by beds of fireclay, coal, and limey shale, discovered some years 
ago by Mr K. G. Carruthers, and which yielded to him specimens of 
Posidonomya becheri and Pterinopecten papyraceus. This bed appears 
to form a well-marked horizon in the district. 
Proceeding upstream we see outcropping on the right bank the 
Blackbyre Limestone, 2 feet thick. It is a cement in the upper part, and 
