40 
SUPPLEMENTARY OBSERVATIONS ON THE GLACIER LAKES 
OF CLEVELAND. 
BY PERCY F. KENDALL, F.G.S. 
The paper in the Quarterly Journal of the Geological Society 
(Vol. LVIII.), of which the foregoing is an abridgment was. 
extended at great length by the obligation which I conceived 
to be cast upon nie of not only dealing with a complicated train 
of phenomena, but also of laying before geologists evidence of 
factors in the glaciation of this country which had not been 
dealt with by any previous writer. I found, however, that even 
the generous amount of space allowed me for the exposition of 
the subject was insufficient, and many points of great interest 
were passed over without as full a treatment as I think their 
importance demanded. Questions, moreover, arose in the dis- 
cussion on the paper, and during the excursion of the Yorkshire 
Geological Society to Cleveland, which I desire to clear up. 
(1) Overflow V alleys with Two- fold Drainage. — I mentioned two 
overflow channels at the north-eastern angle of the Silpho Moors, 
each of which seems to indicate alternate flow of lake waters 
from east to west and from west to east through the same channel, 
an alternation which I had already shown (Q.J.G.S., Vol. LVIII., 
p. 554, 3rd par.) to be a priori probable, as there were possible 
outlets at both ends of the escarpment which might by slight 
fluctuations of the ice-front be opened alternately. 
On the occasion of tlie excursion to Whitby and Scarborough 
I explained my reasons for this interpretation, and I take tliis 
opportunity of placing them on record. 
An outstanding spur is cut through by successive parallel 
channels, the small outer one being at a considerably greater 
elevation than the inner one, which contains Throxenby Mere. 
The outer channel shows most clearly the characters I wish to 
describe, and I will therefore confine my attention to it. A 
section along the floor of the valley shows that it is crossed by 
