G. W. Tyrrell — Intrusions of Kilsyth-Croy District. 301 



mass of the Kilsyth-Croy intrusion, for instance, lies between the 

 Index Limestone and the Kilsyth Coking Coal; yet in the south- 

 western prolongation of the Croy mass 

 it has transgressed so as to actually 

 overlie the former seam. To the 

 north-east, however, it transgresses 

 downwards.^ A detailed section across 

 the area from the north-west to south- 

 east shows at once that the apparently 

 separate masses of Kilsyth and Croy 

 are detached portions of the same 

 intrusion thrown off on either side of 

 the denuded anticline of the Kiggin 

 (see Fig. 1). In the extreme north- 

 east of the area, towards Denny, the 

 two outcrops unite where both the 

 intrusion and the anticline are be- 

 ginning to die out. The sinuous out- 

 crop 1 mile to the south of the Croy 

 Mass belongs to a thin intrusion 

 injected on a platform some hundreds 

 of feet higher in the series. To the 

 north of the Kilsyth Mass a small 

 intrusion occurs on a lower platform, 

 and abuts against the boundary fault 

 between the Carboniferous Limestone 

 Series and the Calciferous Sandstone. 

 It is probably the same as that which 

 occurs in a deep bore at Wester Bedcow 

 near Kilsyth. This horizon is about 

 270 feet above the Main Coking Coal. 



The horizon of the intrusions becomes 

 lower as one proceeds in a north- 

 westerly direction. The great sill of 

 Stirling in this direction is injected 

 just above the Hurlet Limestone, at 

 the base of the Carboniferous Limestone 

 Series. 



The intrusion trending southward 

 from Myot Hill, which appears to be 

 the southern continuation of the 

 Stirling mass, is just under the horizon* 

 of the Main Coking Coal at the out- 

 crop. A boring in Messrs. A. & G. 

 Moore's Castlerankine field, half a luile 

 east of the outcrop, shows that in this 

 distance the igneous rock has trans- 

 gressed until it is- at least 400 feet 

 below the Coking Coal. 



1 Ibid., 1906, p. 104. 



