18 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
ably discussed in the reports which you have heard that 
I need not repeat what has already been so well put 
before you. I would only say that the thanks of the 
Society are due to those gentlemen by whom the reports 
have been prepared for the great interest they take in the 
affairs of the Society, and the time and labour they devote 
to its service. May they long be with us, and may their 
reports in the future continue to be as gratifying as they 
have been in the past. 
Now that the prospect of obtaining a suitable Museum 
in which to display the natural resources of Perthshire 
is so soon to be realized, it behoves each member of 
our Society, as I have said, to do his utmost to in¬ 
crease the collections which we already possess. These 
form an admirable nucleus, but if we are to have 
such a collection as I sketched in outline in my address 
of last year, each of us must be prepared to work, and 
to work with a will. It has occurred to me, therefore, 
that I could hardly occupy your time to-day to better 
advantage than by throwing out a few hints as to how 
those of you who are “ geologically-minded ” may set 
about investigating the primeval history of Perthshire 
with most advantage to yourselves and our Museum. 
The various rocks of which this county is made up are 
much more numerous than is generally supposed, but they 
all belong to one or other of these “ formations”:—namely, 
Silurian, Old Red Sandstone, Carboniferous, Miocene, 
Glacial, Postglacial, and Recent. 
The oldest of these formations is, of course, the Silurian, 
which extends over all the Highland portion of the 
county. It consists of a great succession of various 
kinds of schists (amongst which mica - schists predo¬ 
minates), gneissoze rocks, quartz-rock, flagstones, grey- 
wacke, grit. clay-slate, limestone, &c. All these rocks 
occur as bedded masses: they are arranged in layers 
or strata,- which are usually inclined at a high angle; 
and not only so, but when the strata are viewed on the 
large scale they are seen to have a particular trend. That 
is to say, their edges or outcrops run in a more or less 
determinate direction, which is from south-west to north¬ 
east; so that in travelling by the Highland Railway you 
pass across the outcrops of the Silurian strata as near as 
may be at right angles. Now if we carefully noted upon 
a map all the various dips or inclinations of these Silurian 
strata which may be observed between Dalnaspidal and 
Dunkeld, we should find that sometimes the beds dipped 
to north-west and sometimes to south-east. Por example, 
at and near Dalnaspidal the strata incline to north-west; 
coming down Glen Garry, however, we should note that 
the direction changes to south-east—a dip which, with 
some local irregularities, continues all the way to the Pass 
of Killiecrankie, where the beds rise up, as it were, and 
begin to dip once more to north-west. Shortly after 
passing Pitlochrie the dip again changes to south-east, and 
then we cross a series of rocks in which little or no good 
evidence of dip can be obtained,— the separate beds, when 
these can be distinguished, seeming to be frequently 
vertical, but with an inclination to dip to south-east. And 
so at last we come upon the Birnam and Dunkeld slates, 
which there can be little doubt occupy the highest position 
amongst the Silurian strata of Perthshire. Now, these 
various dips indicate the position of certain foldings of the 
strata, which, having been originally laid down in hori¬ 
zontal or approximately horizontal layers, have come in 
time to be squeezed up into great undulations, so as to 
form a series of anticlinal axes and synclinal troughs. 
To trace out the direction of these vast crumplings of the 
strata, in a more detailed manner than has yet been done, 
would be a most interesting and instructive task for the 
members of this Society. Por it practically means the 
unravelling of the structure of the Highlands, and ascer¬ 
taining the relative antiquity of the various rock-masses 
of which those mountain-tracts are composed. 
While endeavouring to accomplish this object, the local 
geologist would make acquaintance with a great variety of 
rocks. He would come across quartz-rock, gneiss, and mica- 
schist in the Athole district; slates at Birnam; micaceous 
flag-stones, grits, and grey wacke over vast tracts, extending 
from the borders of Stirling, across the Braes of Bal- 
quhidder, Loch Earn, Strathbraan, and north-east to the 
confines of Pcrfarshire. Limestone he would note in not 
a few places, as on the shores of Loch Tay, in Glen 
Lyon, in the Tummel below Loch Rannoch, in Glen Tilt, 
at Pitlochrie, and elsewhere. Besides these rocks, which 
are the prevailing varieties, the observer would encounter 
many other crystalline rocks, some of which are of 
metamorphic origin, while others are igneous. There are 
granite, diorite, felsite, quartz-porphyry, syenite, horn¬ 
blende-porphyry, and many more. Were specimens of all 
these obtained, their localities and positions being carefully 
noted, it would be seen what a rich field of research lies 
open to the mineralogist and petrologist in the picturesque 
Highlands of this county. 
Although no fossils have ever been recorded from 
the Silurian strata of Perthshire, I do not think that 
all hope of detecting them needs be abandoned. In 
many wide tracts in the Silurian uplands of Southern 
Scotland which used to be considered barren of organic, 
remains, these have of late years been discovered again 
I and again; and the same may well be the case with some 
