298 BATHYMETRICAL SURVEY OF 



from end to end, roughly approximating with the outline of the loch. 

 The principal 50-feet basin extends from the narrows for a distance of 

 three-quarters of a mile down the loch, and there is an isolated sounding 

 of 52 feet to the north-west of the narrows. The 75-feet basin is a long 

 and narrow area, half a mile in length, the deepest sounding having 

 been recorded at the upper end of this basin, and comparatively close to 

 the south-western shore, off which the slope is steep. This is well shown 

 in the cross-section E-F on the map, and at other places along both 

 shores the soundings indicate steep slopes. The longitudinal section 

 A-B shows the shoaling of the water at the narrows, deepening 

 immediately to the south-east to the maximum depth of the loch; 

 there is also a scarcely perceptible shoaling farther down the loch, 

 where a sounding of 37 feet was recorded, with 47 feet to the north- 

 west and 41 feet to the south-east. The areas between the consecutive 

 contour-lines, and the percentages to the total area of the loch, are 

 as follows : 



to 25 feet 190 acres 43 per cent. 



25,, 50 198 45 



50 75 37 9 



Over 75 14 3 



439 100 



These figures show that the average slope is slightly steeper within 

 the 25-feet line than between 25 and 50 feet, and they also show how 

 circumscribed is the area deeper than 50 feet, 88 per cent, of the lake- 

 floor being covered with less than 50 feet of water. 



Temperature Observations. A series of temperatures taken in the 

 deepest part of the loch at 6 p.m. on the date of the survey gave the 

 following results : 



Surface 56'8 Fahr. 



25 feet 56'2 



50 , 56-0 



80 ' ... 55'8 ,, 



These observations indicate a range of only 1 from surface to 

 bottom. 



Loch a' Ghriama (see Plate LXVIL). Loch a' Ghriama (or Griam) 

 lies immediately to the north of the head of Loch Shin, into which its 

 waters are carried by a short rapid stream. The distance between the 

 two lochs is only a quarter of a mile, and at the time of the survey 

 there was a difference in level of nearly 33 feet. It is a good trout 

 loch, and Salmo feroz is also found in it. The principal feeder is the 

 Amhainn an Ceardaich, over a mile in length, bearing the outflow 

 from Loch Merkland. It trends almost north and south, and is 1J 





