98 J. F. CAMPBELL ON GLACIAL PERIODS. 
8. GuactaL Pertops. By J. F. Campsztt, Esq., F.G.8. 
(Read June 20, 1877.) 
I. Introductory. 
1. I first saw a glacier in the Alps in August 1841, when travel- 
ling was more difficult than it isnow. The term “ Glacial Period” 
is not much older, and now is commonly used as if it were a proved 
historical event. Advanced glacialists speculate on the geological 
effects of an “ Ice-cap” which extended from the North Pole to the 
Equator, which nearly filled the bed of the ocean, which surrounded 
Britain with a wall of ice and a freshwater moat, blocked up the 
drainage of continents, extinguished life on earth, or left only a few 
survivors in hollows nearly dried up by the evaporation of oceans 
needed to make the polar snow-heaps from which the “ Ice-caps” 
spread over the earth during the “ Glacial Period.” Astronomical 
causes (changes in the sun, in the paths of planets, and in their axes 
of rotation) have been summoned to account for the climate imagined. 
All these theories rest upon some observed facts. Since more facts 
have been collected, the majority of observers, field-geologists, and 
travellers have given up the “Ice-cap ;” but many geologists, and the 
public in general, still continue to use the term ‘“ Glacial Period ” 
without limitation. It has long appeared to me that our Society 
ought to have an opinion on this branch of superficial geology. In 
order to start a debate on the subject, I venture to offer this paper 
to the Society, and to state my opinion. My opinion is, that no geo- 
logical record eaists of any abnormal “ Glacial Perwod” colder than 
the present world’s climate. But if the term “ Glacial Period” be 
used with a limitation such as “local,” or “ Alpine,” or “ Huropean,” _ 
LI have nothing to object. 
2. I will shortly state how that opinion was formed, so that the 
worth of it may be estimated by those who differ from it. 3. Since 
1836 I have travelled a long way, and I have sketched a great deal, 
striving to copy on paper landscapes which were pictured in my eyes 
so as to aid memory of form. Ever since I first saw glaciers and 
their marks, I have studied glaciation wherever I have been. 4. In. 
1865 the results of observations made in Europe, in Iceland, and in 
America were published in ‘ Frost and Fire,’ vol. ii. 5. Im the 
same year observations made on the coasts of Labrador and New- 
foundland, in Canada, and in the United States were published in 
‘A short American Tramp,’ 1 vol. 6. In May 1873 a paper pub- 
lished in the ‘ Quarterly Journal of the Geological Soviety of London,’ 
on the Glaciation of Ireland, stated facts, opinions based on them, 
and problems. I had hunted ice-marks from Cape Clear to Edin- 
burgh. 7. In November 1873 a paper in the same Journal, on the 
Glacial Phenomena of the Hebrides, stated facts recently gathered, 
and difficulties in accounting forthem. 8. In November 1874 a third 
paper in the same Journal, “ About Polar Glaciation,” gave the results 
