PROCEEDINGS OP THE PERTHSHIRE SOCIETY OE NATURAL SCIENCE. 
5 
giving a description of the so called “Head” of Devon¬ 
shire, Cornwall, &c., and the similar accumulation upon 
the coast of Normandy, Dr Geikie went on to give 
some account of the clay-with-flints of the Paris Basin 
and the great consolidated debris - heaps or breccias of 
Gibraltar. By means of sections across the Bock he 
showed the position of these breccias, and explained how 
they had been formed at two different periods, separated 
by a considerable time, during which the Rock of Gibral¬ 
tar was submerged for some hundreds of feet. After re¬ 
marking upon the fact that similar breccias occurred in 
Corsica, Sardinia, Malta, Italy, Cyprus, and other places, 
he proceeded to explain the mode in which they, the 
“Head” of Cornwall, the ancient debris-heap of Scot¬ 
land, and similar formations elsewhere, had been accumu¬ 
lated. The angular fragments had been dislodged from 
the rock of which they once formed a part by the action of 
frost. But they could not have rolled to their present 
position upon the low grounds by the mere impetus ac¬ 
quired by them when they were disrupted from the rocks 
above. They would naturally come to rest upon the low 
grounds at the base of the cliffs, unless some other force 
than the mere impetus of their fall had been urging them 
forward. We now meet with them at distances of many 
hundred yards away from the foot of the cliffs and steeper 
slopes; and to have reached their present positions, they 
have travelled over a surface-slope not greater in many 
cases than 5°, or even 3°. The debris speaks not only 
to the action of hard frost, but of heavy gnows. It was 
the melting of the latter and the saturation of the debris- 
heaps which caused the rubbish to flow as it were out¬ 
wards from the base of the cliff, and doubtless this action 
was still further favoured by the alternate freezing and 
thawing of the water-soaked masses. It might seem 
strange to speak of snows and hard frost in the islands 
and along the borders of the Mediterranean, but the evi¬ 
dence of former colder conditions was not by any means 
restricted to the ancient debris-heaps or breccias. In a 
few words, Dr Geikie then sketched the broad results 
which had been arrived at by glacialists as to the former 
extent of the European snow-fields and glaciers during 
the Glacial Period, and he showed that these, taken in con¬ 
nection with the evidence furnished by organic remains, 
both animal and vegetable, abundantly confirmed the con¬ 
clusions to which the phenomena of the ancient rubbish- 
heaps appeared to point. The climate of all Europe had 
been greatly affected ;—not only did an enormous ice- 
sheet, extending from Scandinavia and burying the British 
Isles, creep southward over the plains of Northern Ger¬ 
many, but all the mountain - tracts became centres of 
glaciation. The present glaciers of Switzerland were the 
degenerate successors of great ice-fields which now meet 
with their nearest analogues in the Arctio Regions. And 
many hilly districts in Prance, Spain, and Eastern and 
Southern Europe, which were now destitute of glaciers, 
were formerly the seats of extensive snow - fields and 
glaciers of no mean size. While in other places, such as 
the low grounds of Southern England and Prance, and 
hilly regions bordering on the Mediterranean, where the 
conditions were not favourable to the formation of glaciers, 
considerable snows fell, and hard frost ruptured and 
shattered the rocks. It was to this period of cold that 
most of those great accumulations of rock-debris belonged 
—those natural rubbish-heaps which had now ceased in 
many places to accumulate. They thus bore strong evi¬ 
dence to the former extent and intensity of ice-action dur¬ 
ing the Glacial Period. 
2. “ The Butterflies of the Perth District .” By Mr S. H. 
Ellison. 
In offering a few remarks, practical rather than scien¬ 
tific, on the butterflies of the Perth district, my object is, 
if possible, to create a greater interest among some of the 
members for the study of insect life, and so increase our 
number of entomologists. About two centuries ago, 
naturalists were in the rather unenviable position of being 
looked upon as lunatics, for we read that the will of Lady 
Granville,—whose name one of the Pritillaries still bears, 
—was disputed on a point of insanity, the only evidence 
produced being her fondness for collecting insects. Happily 
we live iD better times, and the entomologist can pursue 
his study even without being thought a fit occupant for some 
asylum. I take this opportunity of impressing upon our 
members the facilities they enjoy in the prosecution of the 
study of the various subjects of natural science over those 
unconnected with this or similar societies. I remember, 
when I first commenced collecting, I felt the want such a 
Society as this supplies, namely, some authority to whom 
I could apply for information as to the habits, localities, 
and especially the names of insects, for being, as I was, 
the sole representative of the net in the place where I 
then resided, I laboured under great difficulties as to the 
names of specimens. The members of this Society, how¬ 
ever, should experience no such drawbacks, for at the 
monthly meetings they have the opportunity of obtaining 
aDy information they may require. I think there is no 
branch of natural history more interesting or instructive 
than entomology, for in whatever direction we look the 
insect world seems replete with wonders. “ I cannot,” 
says Swammerdam, “ after an attentive examination of 
the nature and structure of both the least and largest of 
the great family of Nature, but allow the less an equal, 
