Correspondence—J. W. Gregory. 239 
THE GLACIATION OF IRELAND. 
Str,—The discrepancies between the directions of ice movements 
shown in Professor Kendall’s enlargement of Mr. Wright’s map, and 
in that by myself (Phil. Trans., vol. 210 B, p. 148) are due in the 
case of the four arrows across the Shannon Valley, near Lough 
Derg, to Professor Kendall having trusted simply to orientation, 
whereas my arrows were drawn in regard to the topography on 
Mr. Wright’s map. For example, Mr. Wright’s southern arrow across 
Lough Derg continues up the Nenagh Valley to the south of the river 
and ends there; so does mine; whereas Professor Kendall’s is con- 
tinued right across the mountain Slieve Kimalto. Mr. Wright's 
next line crosses Lough Derg further north and bends round into the 
valley of the Nenagh and reaches it at the bend, where it is joined 
by the Ollatrim ; and I ended it there to avoid carrying it into the 
upper Nenagh. The northernmost of the four lines begins on the 
lower Bunowen River and crosses the Shannon at its confluence 
with the Little Brosna. My line passes through both points, but 
omitted the further continuation, that being less clear and not 
affecting its relations to the Eskers. 
The glaring discrepancy in the north-western corner of Professor 
Kendall’s map, near Clew Bay, is due to its omission of one set of 
Mr. Wright’slines. Mr. Wright’s map shows two movements in Mayo 
crossing one anotlier at or nearly at right angles. Professor Kendall 
has left out one series, thereby suggesting that the two arrows 
on my map showing a northward flow were inserted by mistake. 
I would ask anyone interested to compare Professor Kendall’s 
enlargement with Mr. Wright’s original map (Quaternary Ice Age, 
1914, p. 49). Professor Kendall’s photographic apparatus has 
powers of selection which merit the censure expressed in the last 
paragraph of his letter. 
J. W. GREGORY. 
THE STADDON GRITS. 
Str,—I was much interested in the communication to your 
April issue by Dr. Asselberghs on the correlation between the Mead- 
foots of Devonshire and the Siegenian of the Ardennes, which forms 
an important contribution to our knowledge of the subject. He, 
however, unintentionally I am sure, misrepresents me in suggesting 
that I have referred all the beds usually included in the Staddon 
Grits to the Cultrijugatus zone. As a matter of fact, 1 expressly 
state (Hand. d. reg. Geol., British Isles, 1917, p. 106, note) that 
rocks lithologically similar to the Staddon Grits contain Meadtoot 
fossils. I also emphasize the fact that the Meadfoot Beds include 
a number of horizons. The truth is that an immense amount of 
work remains to be done on the zoning of the Devonian, both in 
North and South Devon and in Cornwall, and, if Dr. Asselberghs’ 
contribution induces some of our local workers to take this up, it 
