208 
Correspondence. 
CORRESPONDENCE. 
On Glacial Erosion : by Prof. J. W. Spencer , M. A., Pli.D. y F.G.S .— 
This paper is a reply to the courteous review of “Glacial Erosion in Nor¬ 
way and High Latitudes,” which appeared in the American Geologist of 
Dec. 1888. A reply to the questions there asked may remove some doubts 
from the minds of those who do not repose in complaisance with one or 
the other of the schools of surface geology. In this paper, I shall fortify 
myself with the observations of early glacialists, who made their studies 
in the Alps, when the glaciers were advancing down the valleys, a condi¬ 
tion which only a very few of our oldest men have seen—phenomena 
not commonly known to the working glacialists of America, a3 their 
papers are difficult of access. 
My reviewer says that Dr. A. Geikie* visited one of the regions des¬ 
cribed by me and came to “contrary results.” My paper was first published 
as “Notes on the Erosive Power of Glaciers, etc,” in the Geological 
Magazine of London, and was not an attempt at a monograph. I shall 
here show how Dr. Geikie’s and my own conclusions do not reflect on 
either of us as observers. I had his paper with me in the field. Here is 
what Dr. Geikie says upon the glacier in question—that at head of 
Holands fjord, just inside of the Arctic circle. “But the feature which 
most interested us was the relation of this large glacier of Fondalen to the 
moraine deposits of the locality. The high terrace so marked along the 
sides of the Holands fjord enters this valley, and extends on the moun¬ 
tain sides, as far, at least, as the foot of the glacier. Hence the gravelly 
plain and the moraine mounds that separate the glacier from the fjord are 
overlooked on either side by a raised sea-beach. In examining atten¬ 
tively the nature of the material of which the mounds nearest the glacier 
were composed, we were struck with the difference between it and the 
loose, coarse character of the ordinary moraine rubbish, and its resem¬ 
blance to the upper boulder clay of Scotland. The glacier is pushing a 
great nose of ice into and over these mounds, so that freshly exposed sec¬ 
tions are abundant. The deposit is a loose sandy clay or earth full of 
stones, among which the percentage of striated specimens is not large'. 
The larger blocks of gneiss and schist appeared to us not to occur in the 
clay, but to be tumbled down upon it from the surface of the glacier. We 
had hardly begun to look over the surface of the clay ere we found frag¬ 
ments of shells, and in the course of a few minutes we picked up several 
handfuls, chiefly of broken pieces of Gyprina islandica , but including also 
single valves of Astarte compressa, etc. We even took out two or three 
fragments which were sticking in the end of the glacier. * * * We 
were looking not merely upon ordinary moraine heaps—the detritus car¬ 
ried down on the surface of the ice and discharged upon the bottom of 
the valley. The glacier was engaged in ploughing up the marine sedi¬ 
ments which had been formerly deposited upon the submerged floor of 
the valley, and on heaps of earth and clay now torn up were thrown the 
gravel and blocks brought down by the present glacier.” 
♦Geological Sketches, by A. Geikie. 
