84 BATHYMETRICAL SURVEY OF 



THE LOCHS OF BUTE. 



THE principal lochs on the island of Bute (see Index Map, Fig. 8) are 

 situated close together in the southern half of the island, close to the 

 county town of Rothesay. They are all narrow and elongate, with their 

 axes running parallel from south-south-west to north-north-east. Owing 

 to lack of boats only Loch Fad and the Kirk Dam were surveyed. Loch 

 Ascog, a mile in length, and half a mile east of Loch Fad, is used as 

 the water supply of Rothesay. 



Loch Fad (see Plate XXXII.). Loch Fad lies immediately south 

 of the town of Rothesay, from which it is about a mile distant. -It lies 

 between dense woods on the west and cultivated land on the east. The 

 greater part of the west shore is formed by a range of low crags, but the 

 north end is gravelly. The east shore is also gravelly in the northern 

 part, but from the rocky wooded knoll of Bardarroch wood southward 

 rock is exposed at many places. 



The length is nearly 2 miles, and the greatest breadth, at the south 

 end, a quarter of a mile. It is a simple basin of very uniform contour 

 and of very moderate depth, with steep sides, nearly flat bottom, and the 

 central depth varying but little from end to end. The loch is greatly 

 narrowed in the middle, but is not reduced in depth there. The maximum 

 depth of 38 feet is a little south of the narrows. There is a terrace 

 laid down by the Barnauld burn. The mean depth is 17 feet, the area 

 rather more than a quarter of a square mile, or about 176 acres, and the 

 volume 232 millions of cubic feet. 



The drainage area exceeds 2 square miles. The only important in- 

 flowing stream is the Barnauld burn. The outflow is by the channel, 

 in length merely the width of the road, leading to the Kirk Dam. When 

 surveyed on August 21, 1906, the surface was 34'5 feet above sea-level, 

 nearly identical with the elevation determined by the Ordnance Survey 

 on June 10, 1896, viz. 34-3 feet. 



The temperature varied only 0'2 Fahr. between the surface (60-5) 

 and a depth of 26 feet ^60'3). 



Kirk Dam (see Plate XXXII.). The Kirk Dam is the northern 

 portion of Loch Fad, and lies close to the town of Rothesay. It is 

 separated from Loch Fad by an embankment, but communicates freely 



