RECORDS OF EXCURSIONS IN AYRSHIRE. 27 



The chief feature of ornithological interest was the breeding 

 colony of black-headed gulls {Larus ridibundus) in Bogton Loch. 

 During the excursion a number of birds was noted, including the 

 yellow wagtail {Moiacilla rati). 



In the entomological department some good things were got, 

 including the caterpillar of the drinker moth (Odonestis potatorid), 

 a fine male of Selenia bilunaria, and four species of stone flies — 

 Chloroperla granulatica, Nemsura Meyeri, N. hymenalis, and 

 Fenetra ftisiventris. 



The geological features of Loch Doon and Glen Ness are 

 exceedingly interesting as indicating in no small degree the 

 intensity and duration of the glacial period, and the amount 

 of combined river and sub-aerial erosion that has taken place 

 since that epoch. Some hundred years ago the level of the loch 

 was lowered by having a mine driven through the rocks at the 

 head of Glen Ness, and this enables one to examine the anatomy 

 of the rock-bound basin of the loch in a manner which no other 

 locality we know of presents. 



Of the existence of the glacial period here there is abundant 

 evidence. The whole area of the loch is hollowed in the Silurian 

 system of rocks (doubtfully set down by the Geological Survey as 

 of Llandeilo age), and a large part, if not the whole, of the area of 

 this hollow has evidently been the work of ice. The machine has 

 gone, but everywhere the implements with which it did its work 

 are lying about. Moraines, some of them of large extent, are 

 scattered about in the loch, here and there conspicuous amongst 

 the debris being large boulders of granite. If we are to judge 

 from what we can see, the whole basin of the loch appears to 

 be smooth and polished, the bosses of rock which rise here and 

 there above the surface of the water being striated in a beautiful 

 manner, telling us, in the most precise language which John Frost 

 can command, that the glacier, which not only filled the hollow of 

 the loch but over-topped all the immediately surrounding heights, 

 moved along slowly but majestically in the direction of the long 

 axis of the loch. As we recede from the sides of the loch the 

 action of ice is still apparent to the practised eye ; the polish and 

 stria? may be gone, the surface of the rocks may even have become 

 hacked from long ages of exposure, but the general glaciated out- 

 line, the roches moiitonnees, glacial debris, and the large boulders 



