196 BATHYMETKICAL SURVEY OF 



the south shore of Loch Eport, between the Oban nara Fiadh basin and 

 Loch Obisary. It is nearly one-third of a mile long and one-eighth of 

 a mile in greatest breadth. It is one of the highest lochs surveyed, being 

 27'95 feet above sea-level on June 7, 1904. It is very shallow, the 

 maximum depth being 9 feet. It drains north into Loch Eport by a 

 short burn. 



The Oban nam Fiadh Basin. This comprises seven lochs, of which 

 the lowest, Oban nam Fiadh, is purely tidal; while Loch Caravat, the 

 largest loch of this basin, is very slightly brackish. Two chains of lochs 

 connect with Loch Oban nam Fiadh. On the east Loch na Coinnich, 

 communicating with Loch na Ceithir-Eileana, and on the south Loch 

 Caravat. West from Loch Caravat lies Loch an lasgaich ; east from it 

 Loch 'ic Colla, connected with which is Loch an t-Seasgain. 



' Loch Oban nam Fiadh (see Plate LXXV.) . This loch is of unusual form 

 among the lochs of North Uist. It is elongate and narrow, over a mile 

 long by a quarter of a mile in greatest breadth, and with a mean breadth 

 of one-eighth of a mile, covering an area of about 92 acres. It is divided 

 into three portions by narrows. The main part is of oblong form, its axis, 

 east and west, two-thirds of a mile long. There are several small islands, 

 one in the centre of the loch. The bottom is uniform, 5 or 6 feet in depth, 

 but with two depressions of 10 feet. The middle and upper portions are 

 small, and 4 to 5 feet in depth. They are separated by a low island, and 

 the whole channel here is grown up with reeds. The stream from Loch 

 Caravat enters the upper basin. The shores are of rock. 



The loch is interesting from the transition it shows from salt to fresh 

 water, and the corresponding difference in the fauna and flora of the upper 

 and lower basins. The lower part is purely tidal. If not filled by all 

 ordinary tides, it is, at any rate, so frequently filled as to enable sea-weeds 

 to grow and marine animals to live. Yet fresh- water plants also grow in 

 this part, and mussels are found adhering to these. The very narrow 

 channel and the dense growth of Phragmites prevent the tides from having 

 much effect on the upper portion in summer. Here the water tastes 

 almost fresh, and such fresh- water Crustacea as Holopedium are found. 

 Yet high tides must raise this part considerably, as Loch Caravat, at the 

 time of our visit 2 feet higher, is filled through *it. The temperature at 

 the surface was 68'0 Fahr., and at 6 feet 66'8, on June 7, 1904. 



Loch Caravat (see Plate LXXV.). Loch Caravat is the second deepest 

 among the larger lochs of the island, though the little Loch a' Ghlinne- 

 Dorcha is somewhat deeper. In general form it resembles the letter H, 

 there being two narrow portions running east and west, connected by 

 a narrow channel running nbrth and south. In these circumstances it is 

 difficult to define length and breadth ; a line drawn from the west end of 



