184 TRANSACTIONS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
original article by Mr. Teall, and to that just cited, as published 
in our Transactions for this year. 
In a paper contributed to the Geological Society of Glasgow in 
the year 1896,1^ the author gave an account of that extensive sill of 
basic igneous rock which underlies the Loch Tay limestone, and is 
generally seen to outcrop to the surface along with the limestone. 
It may be kudied near the village of Killin, at the south-west end of 
Loch Tay, where it is exposed in several fine sections. Along the 
road which leads to the steamer pier, and in the woods of Finlarig, 
the hornblende schist may be seen in contact with the limestone. 
At this point the limestone dips towards the north-west at an angle 
of 45 degrees, and is underlaid by this sill of basic rock. The 
relationship of the basic rock to the limestone may also be well seen 
in the southern front of Sron Clachan, from which point it may be 
traced to the south side of the glen at the head of Glen Ogle. 
Down Glen Ogle various exposures of the basic rock in contact with 
the limestone may be observed. Traced round to Glen Beich, a fine 
section of the hornblende schist is exposed at the foot of that glen. 
The limestone and hornblende schist may then be traced at various 
points to the head of Glen Beich, where some fine sections are 
exposed, showing the hornblende schist and limestone traversed by 
numerous veins of pink quartz felsite. An interesting outlier of 
limestone with the accompanying sill of basic rock may be seen at 
the summit of Meal-na-Creig, a mountain situated to the south-east 
of Ardeonaig. This mountain is also traversed by a series of mineral 
veins which were at one time mined for galena. We think there can 
be no doubt that this mass of basic rock must have originally been 
intruded amongst the clastic rocks in the form of a sill. At certain 
points, as in Finlarig Wood, Killin, the mica-schist shows evidence 
of a more extreme metamorphism along the line of contact with the 
hornblende schists, while at various points it shows evidence of 
breaking across from one horizon to another. Again, smaller sills, 
or apophyses, evidently connected with the main mass, may be seen 
at various points along the line of outcrop. 
Macroscopically, a specimen of the typical hornblende schist is 
seen to be made up of alternating foliae of light and dark coloured 
minerals, which under the microscope are seen to be felspar and 
hornblende. When the rock is highly foliated and shows a marked 
schistose structure, indicating that it has undergone a more or less 
intense metamorphism, the felspars generally exhibit a granular 
appearance, as it they were of clastic origin. This structure is 
now well known to be the result of the shearing of the rocks by 
earth creeps, which have crushed and broken the felspars into 
this granular form. In the more schistose types of these altered 
