PROCEEDINGS OP THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
235 
728 feet. The aspect of the cliffs is south by south-east, and 
a one point their greatest nearly perpendicular altitude is 
more than 200 feet. 
The district is on the whole a dry one. One very insig¬ 
nificant burn traverses about one quarter of the western 
slope, while the Tay bounds it on one side and a little part 
of the very small Deuchny Burn touches another. Nor 
can it be said to have any marshes within its boundaries, 
though there are here and there some very limited pieces of 
slightly damp ground. Rather more than the eastern half 
of the area is covered by woodland, while a strip of about 
one-third of a mile in breadth along the western boundary 
is occupied by houses and gardens, and most of the remain¬ 
ing portion is under cultivation. 
While almost the whole of the western half is within the 
Parliamentary boundaries of the city of Perth, a not 
inconsiderable portion of the north-western corner is 
actually within the municipal boundaries, and forms part 
of the town itself. 
Of the former conditions of Kinnoull Hill, we unfortu¬ 
nately know very little. Writing in 1774, Cant, in his 
edition of Adamson’s Muses Threnodie, says that the 
northern and western slopes were anciently covered by a 
forest of oaks, “which produced the great beams in St 
John's Kirk above four hundred years ago.” For many 
years before he wrote it had been little better than 
a barren common, but about this time (1774) the 
various proprietors had begun to form plantations, and 
to their efforts we owe the pleasant woods with which the 
hill is now adorned. Much of the wood, however, must be 
of a more recent date even than this. 
In concluding this introduction, this opportunity must 
not be passed over of expressing the debt of gratitude that 
the inhabitants of Perth in general, and we as naturalists 
in particular, owe to the proprietors of the hill, and especi¬ 
ally to the Earl of Kinnoull, for the privilege of more or 
less free access to it. 
Note ,—Since it might be objected that by publishing 
the localities of the rarer plants and animals of Kinnoull 
Hill, the danger of their extermination by unscrupulous 
persons might be incurred, it may be mentioned that in 
any instance where this is at all likely to be the ease, 
Kinnoull Hill is already known as a locality, and hence 
no harm can be done by republication. 
II.— The Geology. 
By Professor James Geikie, LL.D., F.R.S. 
Kinnoull Hill, with Caller Fountain Hill and Moncreiffe Hill, 
may be said to form the south-west termination of the Sidlaws. 
The Sidlaws, however, are only a subordinate portion of that 
long belt of high ground, which, with several interruptious, 
extends from the coast-lands near Stonehaven south-west across 
the whole breadth of Scotland to the shores of the Firth of 
Clyde at Ardrossan. This belt of high grounds I have elsewhere 
designated as the Northern Heights of the Lowlands. A long 
narrow depression separates these heights from the Highlands— 
a depression which reaches its greatest width in Strathmore. 
Kinnoull Hill, which is 728 feet above the sea-level, presents 
a steep escarpment to the south,—the upper 200 feet forming a 
cliff which slopes at an angle of 60 degs. Below this the angle 
of slope is less,—the average for the succeeding 300 feet being 
about 46 degs.,—from which, down to the alluvial plain of the 
Tay, the inclination is very little more than 20 degs. Towards 
the north the hill falls away with a comparatively gentle slope, 
the average inclination from the top of the hill to the road near 
Muirhall Toll-bar being hardly more than 7 degs., or 1 in 8. 
Towards the west the declivity is steeper,—the average inclina¬ 
tion from the summit to the road at Barnhill being about 10 
degs., or 1 in G. Going towards north-east, we find, as already 
observed, that Kinnoull Hill forms a portion of that well-marked 
belt of high ground, the Sidlaw Hills. 
PETROLOGY OP KINNOULL HILL. 
The rocks which enter into the composition of Kinnoull Hill 
show no great variety. There are representatives of the two 
chief classes, viz., Crystalline and Fragmental,—the former 
consisting of igneous and the latter of aqueous and aqueo- 
igreous rocks. 
1. Crystalline Rooks. -These are chiefly porphyrites, but 
augitic rocks (basalt, diabase, &c.) are also met with, Forphy- 
rites form nearly the whole surface of Kinnoull Hill,—the most 
prominent variety being a dark purplish blue rock, with a fine¬ 
grained base, scattered through which are conspicuous crystals 
of plagioclase. In some places the rock is highly vesicular and 
amygdaloidal—the amygdules consisting as usual of calcite, 
green earth, quartz, calcedony, jasper, &c. Under the micro¬ 
scope these fine-grained rocks show a finely crystalline ground- 
mass composed of small rod-like crystals of plagioclase and 
granules of pyroxene, mica, magnetite, or ilmenite. Scattered 
through this ground-mass occur larger crystals of plagioclase, 
often accompanied by hornblende, augite, or mica. Traces of a 
glassy or devitrifled base are occasionally met with. Very few 
of the porphyrites do not show traces of alteration. Usually the 
basic silicates are more or less altered, and replaced by 
secondary or decomposition products. These porphyrites occur 
in broad sheets, which vary much in thickness—60 or 60 feet 
being a common thickness for individual beds: occasionally, 
however, they are thicker, and not infrequently they do not 
exceed 12 to 15 feet in thickness. The upper and lower portions 
of each bed are generally more or less vesicular, as is common 
in modern lava-flows. These and other phenomena are well 
exposed in the great cliff, but they may also be studied all over 
the surface of the hill wherever the rock is sufficiently exposed; 
but as all the porphyrites are more or less weathered and 
crumbling, it is hard to get typical specimens showing the 
