370 



BATHYMETRICAL SURVEY OF 



end, and tapering all the way to the outflow. Half a mile from the 

 north end a rocky promontory, the Rudha Ceann Ard Thonnaich, 

 constricts the loch, but there is no shallowing in the narrows, where 

 the depth is well over 200 feet. The basin is quite simple, all the 

 contours approximately following the shore-line. The steep slope of 

 the hills is continued under water, and there is in most parts but little 

 beach. The axis of the loch is slightly curved, and the line of greatest 

 depth is nearer the west shore. The area over 400 feet deep is very 

 narrow, about 2 miles in length, and at both ends comes very close to 

 the west side, the steepest slopes in the loch being at these points. The 



FIG. 56. LOCH TREIG. 



(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.) 



cross-sections in the middle parts of the loch, as at C-D on the map, 

 only show slightly the U -shape which distinguishes glacier-hollowed 

 lochs. The valley is so narrow, relatively to the depth of the loch, 

 that the steep slopes reach far towards the middle, and leave but little 

 comparatively level bottom. Towards the south end, where the loch 

 is broader, and the depth less (from 200 to a little over 300 feet), there 

 is a greater extent of nearly flat bottom, and the U -section is more 

 clearly marked. The approximate areas between the consecutive 

 contours at intervals of 100 feet, and the percentages to the total area 

 of the loch , are given in the following table : 



