244 BATHYMETRICAL SURVEY OF 



same gillie stated that a shoal bank extended from Ruadh Bac na Moine 

 in an approximately south-west direction towards the opposite shore; 

 this was confirmed by fishermen, and is probably indicated by the 

 outward bend of the 50-feet contour-line at that place. 



The 100-feet contour-line is less sinuous in character than the 50-feet 

 contour, the main basin being about 12 miles in length, extending 

 from near the head of the loch to the narrows at Eilean Fhianain, 

 with two small subsidiary basins one off Rudha Leathan, about 3J 

 miles from the foot of the loch, based on a sounding of 112 feet; 

 the other between the promontory on the south-eastern shore called 

 Rudha Torr a' Chonnaidh and the outlying islands, about 7 miles from 

 the head of the loch, based on a sounding of 148 feet. A remarkable 

 rise in the bottom was observed within the main 100-feet basin, about 

 a mile above the entrance of the river Polloch, where soundings of 

 84 and 43 feet were taken, surrounded on all sides by about 150 feet 

 of water. The contour of the lake-floor along this line of soundings is 

 shown in cross-section C-D on the map (Plate LII.). 



The main 200-feet basin is nearly 8 miles in length, approaching 

 to within half a mile from the head of the loch, and extending as far 

 down as Eileanan Comhlach. There are two small subsidiary basins, 

 separated from the main basin by an interval of over half a mile, 

 between the entrance of the Allt na Claise on the south-eastern shore 

 and the entrance of the An Garbh-allt on the north-western shore. 

 This line of soundings shows a curious configuration of the bottom, 

 which rises in the central part of the loch and sinks again on both sides 

 nearer the shore : thus, on proceeding from south-east to north-west the 

 water deepens to 201 feet, then shoals to 122 feet, then deepens again to 

 172, 209, and 224 feet, shoaling again towards the north-western shore. 

 It is interesting to note the close proximity of these two small deep 

 basins to the rise covered by 43 feet of water already mentioned. The 

 200-feet contour shows a peculiar loop off the north-western shore, 

 about 4 miles from the head of the loch, where the water shoals from 

 199 to 163 feet. 



The principal 300-feet basin is distant about a mile from the head 

 of the loch, and extends down the loch for over 4 miles, enclosing the 

 deepest parts of the loch. Separated from this basin by an interval 

 of a quarter of a mile (in which the greatest depth is 282 feet) is a 

 second small basin based upon a sounding of 307 feet, and after a 

 similar interval (in which the greatest depth is 284 feet) there is 

 a third 300-feet basin 2 miles in length, having a maximum depth of 

 385 feet. Within this third basin there is a slight rise of the bottom 

 covered by 288 feet of water; the line of soundings on which this 

 rise is situated is shown in cross-section E-F on map (Plate LIIL). 



There are two small basins with depths exceeding 400 feet, the 

 smaller about 3 miles from the head of the loch, based on soundings 





