20 BATHYMETRICAL SURVEY OF 



LOCHS OF THE FORSS BASIN. 



THE Lake Survey staff sounded the two principal lochs within this basin, 

 viz. Lochs Calder and Shurrery. The few smaller lochs of which the 

 most important are Loch Olginey flowing into Loch Calder, and Loch 

 Chaluim flowing into Loch Shurrery could not be surveyed for lack of 

 boats. The headwaters of the basin take their rise on the flanks of Beinn 

 nam Bad Mhor and Cnoc an Fhuarain Bhain, flowing by the Cnocglass 

 or Torran water into Loch Shurrery, from which issues the Forss water, 

 which on its way to the sea is joined by the Alltan Glminne, bearing the 

 overflow from Loch Calder. Like most of the Caithness lochs, Loch 

 Shurrery is shallow, while Loch Calder is important both on account of 

 its depth, and because it is the source of the water-supply to the town of 

 Thurso. The fishing in both lochs is good, though preserved ; salmon and 

 trout being got in Loch Shurrery, and trout and char in Loch Calder. 



Loch Shurrery (see Plate VII.). Loch Shurrery lies about 8 miles 

 from Thurso and 7 miles from Reay, on the north coast of Caithness. 

 The loch trends in a north and south direction, and is 1 miles in length, 

 the maximum width being less than half a mile. Its waters cover an area 

 of about 228 acres, or over one- third of a square mile, and it drains an 

 area of 29 square miles. The maximum depth of 7 feet was observed in 

 two places near the middle of the loch towards the eastern shore, and 

 near the foot of the loch towards the western shore. The volume of water 

 is estimated at 43 million cubic feet, and the mean depth at 4J feet. The 

 loch was surveyed on October 6, 1902, when the elevation of the lake- 

 surface was found to be 321*45 feet above the sea ; when levelled by the 

 Ordnance Survey officers on June 4, 1870, the elevation was 321'1 feet 

 above sea-level. Loch Shurrery is a shallow, flat-bottomed basin, the 

 majority of the soundings having been taken in depths of 5 and 6 feet, 

 while three soundings were taken at the maximum depth of 7 feet two 

 near the centre and one near the northern end, as already indicated. The 

 area of the lake-floor covered by more than 5 feet of water is about 121 

 acres, or 53 per cent, of the total area of the loch. The temperature of 

 the surface water towards the southern end was 50*0 Fahr., while towards 

 the northern end readings at the surface and at a depth of 3 feet gave 

 49'5, and a reading at 5 feet gave 49-2. 



