150 BATHYMETRICAL SURVEY OF 



extends from about a quarter of a mile from the east end to Rudh' an 

 Alt-toir, and is 4f miles in length. The four areas exceeding 200 feet 

 in depth, proceeding from east to west, are (1) a large eastern basin 

 1J miles in length, extending from south-east of Ardvreck Castle to 

 north of Garbh Dhoire ; (2) a small basin lying 150 yards to the west 

 of the first-mentioned, based on a sounding of 210 feet; (3) a large 

 western basin 1| miles in length, extending from south of the eastern 

 islands off the north shore to north of Torr a' Chail; and (4) a small 

 basin less than 100 yards further west, based on a sounding of 214 feet. 

 The three 250-feet basins are all very narrow, one enclosed in the large 

 eastern 200-feet basin, |-mile in length and with a maximum depth of 

 264 feet, the other two enclosed in the large western 200-feet basin, the 

 smaller having a maximum depth of 270 feet, the larger being nearly a 

 mile in length and including the maximum depth of the loch (282 feet), 

 which occurs to the north of Eilean Assynt. It will be observed that 

 the deep channel does not coincide with the central axis of the loch, but 

 lies for the greater part of its course much nearer the southern than the 

 northern shore ; opposite Ardvreck Castle, however, it crosses over and 

 lies nearer the northern shore in the eastern end of the loch. The 

 numerous large bays along both shores were found to be fairly deep. 



The areas of the lake-floor at different depths, and the percentages 

 to the total area of the loch, are as follows : 



to 50 feet, 572 acres 29 per cent. 



50 ,, 100 559 28 



100,, 150 351 18 



150,, 200 270 14 



200,, 250 184 9 



Over 250 , 46 , 2 



1982 , 100 



More than half the entire lake-floor is covered by less than 100 feet 

 of water, and the areas on both sides of the 50-feet contour-line are 

 nearly equal, indicating a moderate and uniform average slope down 

 to the depth of 100 feet, beyond which depth the slope becomes much 

 steeper. 



Loch Assynt was surveyed on September 12 to 18, 1902. On the 

 12th the elevation of the lake-surface above the sea was determined, 

 by levelling from bench-mark, as being 215*1 feet; subsequently heavy 

 rains set in, so that on the 16th the water had risen to the extent of a 

 foot, and on the 18th to the extent of 16 inches, above the level on the 

 12th, and the later soundings were corrected in order to bring them 

 into agreement with the earlier ones. When levelled by the officers of 

 the Ordnance Survey on September 9, 1871, the surface of the water 



