Clil PROCEEDINGS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
The chief lesson for us, it seems to me, in studying the geology of 
the Grand Canon, is that it enables us to realise the enormous 
amount of denudation which must have taken place in our own 
country, where one formation rests unconformably on another, and 
where the present rocks represent only the small ruins of former vast 
extents of sedimentary deposits. 
Appendix—Notes on Damage caused by Flooding in the Tay Valley 
in January, 1903, by John S. Grant, Ballinluig. —Three attending circum¬ 
stances or conditions account for the extraordinary flooding on 31st January, 1903. 
(1) Exceptional rainfall; (2) rapid thaw, after heavy snowfall on the hills ; and (3) 
fierce and continued gales from the west and south-west. Specially in regard to 
Loch Tay is this the case, for its long winding, comparatively narrow shape, lends 
itself to the terrific wind storms that literally blow the overflowing Loch to the 
Kenmore end. Both Glen Dochart and Glen Lochay, at the Killin end, are 
narrower and steep, and here, as well as along the Loch sides, the hill streams 
bring down their torrents of melted snow. The wide valley, to the west of 
Aberfeldy, is the first tract of arable land where the swollen river takes possession. 
No embankments are sufficient to confine the stream, and even ordinary flooding 
causes stoppage of traffic towards Weem, because the levels of the haugh lands are 
below that of the flooded and confined river; but the actual rise of water, as seen 
in the submerging of fences, walls, hedges, and roadways, until boats could be 
sailed from side to side of the valley, can hardly be believed. Were it not that the 
stream is sluggish, and the fall gradual, the general damages in this part would be 
more serious and apparent. No doubt much of the soil is washed away, and 
deposits of sand left instead ; but there do not appear to be the same tremendous 
bursts, with mountains of gravel, stones, and sand thrown out on the fields as 
lower down the Tay Valley, or along the shorter course of the Tummel. This 
submerging of the entire valley is again seen from the haughs below Pitnacree, to 
the narrows, just at Logierait Bridge and Ferry. On this occasion, even the 
Ballechin banks have suffered little, though for two months the floods have not 
decreased to allow the arable land to be seen. 
The Tummel, in its rapid course from the Loch to below Pitlochry, is so much 
confined, running as it does in a rocky gorge, that embankments are not required ; 
but when the Dunfallandy haughs open out, there the floods at once take posses¬ 
sion, and make a straight course to the sea, over and through every obstruction, the 
natural channel of ordinary use being quite obliterated. Just below Tomdachoill, 
on the south bank, the first break occurs. Of this one we have not yet taken a 
photo. A little lower down, on the Moulinearn side, are two wide gaps. (Plate 
1.) This view shows the new channel forced by the flood first over, then through 
the strong embankment. One end of the gap is seen, with pool and gravel, stones 
and soil washed right out on fields. There is another gap a little further down, 
but the excavation here, and deep pool left, with the silting of material, and end of 
damaged embankment, form a striking example of the extraordinary force of the 
flooded stream. A little below Moulinearn, on the opposite side, can be seen 
another gap and displacement of the strongly-built retaining walls. About 40 
yards are torn away, and will meantime result in fields getting out of cultivation, 
being now covered with deposits of gravel and stones, with a washing away or 
arable soil. The embanking and confining the river below Moulinearn has cost 
Flis Grace the Duke of Atholl immense sums in the past, and were it not for the 
