185 
1916-17.] The Hurlet Sequence and the Abden Fauna. 
hill. The Blackball Limestone was formerly wrought at the foot of 
Craigenglen, where it is seen to be faulted against the Hollybush Lime- 
stone, from which a fairly continuous section can be traced to the shales 
above the Blackball Limestone. In Glen Wyncl, immediately to the west, 
the beds lying below the Hurlet Limestone are well shown, including the 
Alum Shale with its characteristic fauna, the Bone Bed, the Lamellibranch 
Bed, and the Brachiopod Bed in ascending order. 
Proceeding to the north side of the hill we find a similar exposure 
in Baldow Glen. The second section given in the Plate at the end 
has been constructed partly from this section and from that exposed on 
the North Hill of Campsie, above the Milton of Campsie. 
We now pass to a consideration of the sections exposed at Corrieburn, 
which we consider to be the most typical of all the sections of the Lower 
Limestone Series to be seen in Central Scotland ; that is to say, it 
contains in the most generalised form all the features of the Lower 
Limestone Series as developed in the East and West of Scotland. If we 
had our choice we would be inclined to supplant the place of the Hurlet 
Section by that seen at Corrieburn. 
At Corrieburn there are four stream sections which, proceeding from 
west to east, may be numbered 1, 2, 3, and 4 respectively. The following 
group of strata can be seen in these streams. It gives a complete section 
of the Lower Limestone Series from the Blackbyre Limestone to the 
Top Marine Band. The table is extracted with slight alterations from 
a paper on the stratigraphy of the limestone lying immediately above 
the Calciferous Lavas in the Glasgow district by Mr H. Conacher and 
myself : — * 
Ft. In. 
H. 27. Sandstone with Spiroplipton cauda-galli passing upwards into Top 
Marine Band . 
26. Shales with Posidonomya corrugata , Lingula , Ortlioce7'as, etc 
G. 25. Limestone (Top Hosie) (Calderwood Cement) . . . .16 
24. Black shales with rich marine fauna ...... 6 
23. Limey shales . . . . . . . . . .12 
F. 22. Black limestone with Bellerophon and Orthoceras (Main Hosie) . 2 
21. Shale 3 6 
20. Sandstone ........... 30 
19. Shale with nodules, Blackball Shale fauna at the bottom . .70 
fl8. Encrinital limestone with small solitary corals (upper part of 
Blackball Limestone) ........ 3 
17. Brown crusted entomostracan limestone (lower part of Blackball 
Limestone) .......... 3 
* Trans. Geol. Soc. Glasgow , vol. xvi, p. 49. 
