76 BATHYMETEICAL SURVEY OF 



the loch. It is half a mile in length, with a maximum breadth of one- 

 third of a mile. The superficial area is about 50 acres, of which 63 per 

 cent, is covered by less than 20 feet of water, and the drainage area is 

 about 1 square mile. The maximum depth of 43 feet was observed off the 

 central part of the western shore. The volume of water is estimated at 

 43 million cubic feet, and the mean depth at 17J feet. The loch was 

 surveyed on May 27, 1903, when the elevation was found to be 777'6 feet 

 above the sea. The surface temperature was 63*0 Fahr. 



Loch Scamadale (see Plate XXIX.). Loch Scamadale lies about 2J 

 miles from the head of Loch Feochan, and about 6 miles south-east from 

 Oban. The loch trends east and west, and is over 1J miles in length, the 

 maximum breadth being about one-third of a mile, and the mean breadth 

 less than a quarter of a mile. The superficial area exceeds one-third of a 

 square mile, or about 226 acres, while the total area draining into it is 

 nearly 13 J square miles, including that draining into Loch na Sreinge. The 

 maximum depth of 145 feet was recorded near the centre of the loch, the 

 mean depth being estimated at nearly 70 feet, and the volume of water 

 at 685 millions of cubic feet. The loch was surveyed on June 1, 1903, 

 when the elevation was found to be 221*0 feet above the sea, or 4 inches 

 lower than that observed by the officers of the Ordnance Survey on July 25, 

 1864, viz. 221-3 feet. 



Tne conformation of the basin is simple, the slope along the southern 

 shore being much steeper than along the northern shore. The contour- 

 lines are deflected southward off the alluvial cone at the mouth of the 

 Eas Ruadh, on the northern shore, apparently as the result of the deposi- 

 tion of material brought down by that stream. The approximate areas 

 between the contour-lines drawn in at intervals of 50 feet, and the 

 percentages to the total area, are as follows : 



Feet. Acres. Per cent. 



Oto 50 79 ... 35-1 



50 100 89 ... 39-4 



Over 100 58 ... 25-5 



226 100-0 



This table shows the somewhat flat-bottomed character of the basin, 

 the zone covered by water between 50 and 100 feet in depth being larger 

 than the shore-zone covered by less than 50 feet of water. 



Temperature Observations. Serial temperatures, taken in the deepest 

 part of the loch, gave the following results : 



Surface 55-0 Fahr. 



20 feet 52-l 



35 47'8 



70 46-4 



140 46-2 



The range of temperature from surface to bottom amounted to 8-8, 

 there being a fall of 2 a -9 between the surface and a depth of 20 feet, and a 

 further fall of 4-3 between the depths of 20 and 35 feet. 



