Correspondence. 525 
and are sharply scratched and scored by striz which bear N 30 W 
and S 30 E. It is a most singular-looking rock-surface, and well 
worth a visit. Its exact situation is in the townland of Lisduff, at 
the south side of the road leading from Moydow to Ardagh, a little 
to the couth of the letters I and S in ‘LISDUFF,’ 6-inch ordnance 
sheet, Longford 19. There can be little doubt as to the glacial 
origin of the striz, as they coincide in direction with other striz 
seen in several parts of the Longford district. 
It is probable, too, that the ice-current came from the NW., or 
up the slope of the hill. We have no actual proof of this at 
Slievegalry; but about ten miles to the westward a very remark- 
able erratic is traceable to its parent rock. It is a hard, homo- 
geneous, amorphous, blood-red jasper rock, and occurs am situ near 
the summit of Slievebawn Hill, 857 feet above the sea. A large 
block of this rock may be seen perched on a drift-covered hill at 
Ratheline, on the east shore of Lough Ree, somewhat less than six 
miles in a direction of S 30 E from the summit. 
The ridges also, whether of rock or drift, and the stream-courses 
in this part of the country, exhibit a general parallelism in this 
direction, as also do most of the observed striew, so that there is 
strong evidence that the district was at one period covered by an ice 
sheet moving from N 30 Wto S 80 E. F. J. Foor. 
GroLocicaAL Survey oF IRELAND. 
Boyz, Iretanp: Oct, 11, 1865. 
PRIMARY AND SECONDARY STRILA. 
To the Editor of the GroLoGicaAL MAGAZINE. 
Srr,—I am glad to find by Mr. Green’s paper in your tast number, 
that he also has remarked the Primary and Secondary striz. In 
this neighbourhood I have observed three sets; the general bearing 
of the oldest being about N 30 E., of the second N 30 W., and of the 
newest nearly EK and W. The first have a similar bearing to the 
axis of the ‘dressed hummocks’ of rock, and also the primary 
striation in the rest of Galway and Clare; the second agree with 
the general bearing of the valley now occupied by Lough Corrib ; 
while the newest are perpendicular to the mouth of the valley that 
lies between Oughterard and Cliften, and also to the east slopes of 
the hills. 
I would therefore suggesé, that the first were made by the move- 
ment from NE. to SW. of the ice-field which is supposed once to 
have covered Ireland—that as the land sank, local systems of glaciers 
were formed, one of which occupied the valley of Lough Corrib, 
while its branches came down the different mountain-valleys. This 
glacier of Lough Corrib formed the second set of striz; and as the 
land was still sinking it gradually melted away, while the glacier in 
the Oughterard valley remained longer and formed the third set of 
striz. Would Mr. Green look at the features of the country in 
which he has remarked the strie, and see if he could account for 
them in a similar way ? J. Henry KInAwAN. 
OUGHTERARD: Oct, 3, 1865, 
