30 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
SUMMER SESSION, 188 1. 
The following Excursions were made :— 
June 2nd. 
1. To Abcrnethy and Mouth of the Earn. 
Starting from Abernethy, the party proceeded to the 
side of the Tay a little below the mouth of the Earn, 
where the peat bed that underlies the carse clay is well 
exposed. 
This peat bed has been carefully studied by Dr Geikie, 
who, in his Prehistoric Europe, devotes several pages to a 
description of it and the information it affords. The rela¬ 
tion of the various strata at this point, to each other, are 
as follows :—Forming the foundation are rocks of Old Red 
Sandstone age, on which rests a mass of till or boulder 
clay deposited as the “bottom-moraine” of the last ice 
sheet that overflowed the Tay valley. Next comes a series 
of gravels, shingles, and brick clays laid down when the 
ice had disappeared but when the climate was still very 
cold, and when the sea reached a height of about 100 feet 
above its present level. It is to this period that the arctic 
shell-beds of Errol belong. At this time there were many 
glaciers amongst the Perthshire hills, and in summer the 
rivers would be greatly swollen by the melting of the ice 
and snow, and large quantities of gravel and shingle were 
brought down by the floods. Upon these gravels and 
brick clays are another series of gravels, sand, and silt, 
which, from the way they are deposited, were evidently 
laid down by the river without the assistance of the sea. 
The sea was then at a rather lower level, and though 
possibly not very much lower than it is at present, still it 
was sufficiently low to admit of the river cutting for itself 
a deeper channel. There is no special evidence as to what 
climate prevailed during the long period during which 
these river gravels were being laid down, but such as there 
is would indicate one somewhat like the present. 
The next layer is that of the peat bed in question, which 
may be said to extend over the whole Carse of Gowrie from 
Dundee to Perth and for a considerable distance up the Earn, 
and varies in thickness from a few inches up to several feet. 
This peat was evidently formed in part in the place where 
it now is, as the remains of trees which grew there can still 
be seen rooted in the silt below, though in other places the 
peat has been carried by water to where it now lies. At 
this time the sea was at a much lower level, and conse¬ 
quently the shore line was much further off. As for the 
climate, it was probably more genial than at the present 
day. It is in this peat that the oldest evidence of the 
existence of the earliest human inhabitant of Perthshire 
has been obtained, in the form of a “ dug-out ” canoe 
which was found many years ago in the Friarton brick¬ 
field. Though the canoe in-question is the only one of 
which record has hitherto been made in connection with 
the Tay, it seems that two others have been found in the 
Tay itself. For information regarding these we are in¬ 
debted to Mr Pitcaithly, Elcho Castle. According to that 
gentleman, these canoes were made of oak, though the one 
found at Friarton appeared to be of pine. 
Above the peat bed lie the deposits of clay and silt 
known as the Carse clays, which vary in thickness 
from 10 to 40 feet. These clays, which cover an area of 
not less than 35 square miles, show that the climate 
was considerably different both from that which prevails 
at the present day and that which prevailed during the 
time that the peat was being deposited. The sea then 
stood at a much higher level—45 feet at least above present 
mean tide; consequently, the whole Carse would be an 
arm of the sea, into which the rivers, greatly swollen ) 
brought down immense deposits of fine silt derived from 
the grinding of the Highland rocks by local glaciers. The 
climate was much colder, aud there was probably also a 
larger rainfall. 
After the laying down of the Carse clays, the sea again 
gradually retreated, and the river deposited the terraces of 
gravel, sand, and silt, which remain as evidences of the 
gradual alteration in the height of the river and the sea. 
Crossing the Earn, the party proceeded to explore the 
west bank of the Taj-. The zoologists of the party found 
the objects of their study rather conspicuous bj r their 
absence, but the botanists were more fortunate. Nearly 
one hundred species of flowering plants were observed 
during the excursion, of which the following are the more 
interesting :—Caltha palustris (the marsh marigold, or 
king cup), a common enough plant, but remarkable for 
the immense profusion in which it grows on the swampy 
sides of the river. The variety called Gfuerangerii, which 
has hitherto been but seen very rarely in Perthshire, was 
found to be very abundant. Trollius europceus (the globe 
flower), with beautiful golden ball-shaped flowers; Carda- 
mine amara (Bitter Cress); Lcpidium Smithii ; Cerastium 
triviale var. holosteoidcs, a very local British plant; Coma- 
rumpalustre (Marsh Cinquefoil); (Enanthecrocata , reputed 
