428 Correspondence—Mr. H. Keeping. 
The formation of the beaches is referred to the waves of a lake 
confined on the south and on either hand by existing highlands 
and divides, and on the north by the retreating ice-sheet of North 
America; the deposition of the Red River silts is attributed to the 
mud-charged waters of the glacial lake; and the excavation of the 
Big Stone-Traverse gorge is ascribed to the corrosion of the effluent 
which conveyed its surplus waters toward the Gulf of Mexico— 
corrosion which was not uniform, and whose temporary cessations 
are recorded in two shore-lines, while its final termination is marked 
by the lowest of the beaches. The departure from horizontality of 
the terraces is referred to the gravitational attraction of the ice-sheet 
upon the waters of the lake. The late General Warren first 
observed that the Big Stone-Traverse Valley (with its extension 
through which the Minnesota River meanders) was manifestly exca- 
vated by a great river, and suggested that Lake Winnipeg formerly 
overflowed into the Gulf of Mexico through this channel; but Mr. 
Upham justly insists that the recent subsidence of the northern part 
of the continent assumed in this hypothesis is disproved by the 
southward inclination of the shore-lines. 
The general hypothesis that the superficial stratified deposits of 
northwardly sloping glaciated regions were laid down and arranged 
in lakes confined between the ice-front and south-lying divides, was 
broached and prominently advocated a decade ago by Belt in 
Europe, and N. H. Winchell in America; and it is to the survivor 
of these geologists that we are now indebted for the inauguration of 
the detailed survey by which complete verification of the hypothesis, 
as applied to a particular region, was rendered possible. 
W. J. McG. 
CORRHBSPON DHNCH. 
pen i 
SECTION AT HORDWELL CLIFFS. 
Sir,— In the discussion upon the paper “ On the Section at Hord- 
well Cliffs from the top of the Lower Headon to the base of the 
Upper Bagshot Sands,” by the late Mr. E. B. Tawney and myself, 
which was read before the Geological Society, June 20th, 1883, 
Professor Judd is reported to have said, 
“That the paper seemed to be a critical one, and the criticism was 
rather of the nature of a statement that the authors had not seen 
what several distinguished observers, such as Mr. F’. Edwards, Mr. 
Searles Wood, Dr. Wright, and others stated they had distinctly 
seen. He himself had seen a portion of the bed in question. This 
bed, which had been seen in situ by so many observers, we were now 
asked to believe was only a squeezed-out mass. It was remarkable 
that one of the authors of this paper [meaning myself] had assisted 
most of the geologists mentioned above, when either he failed to 
persuade them that his present view was the right one, or his memory 
had failed him as to what he then thought on the subject.” 
Now I wish to assure Prof. Judd that my memory does not fail 
me, and that I have seen the fossiliferous patch of stuff in question 
