THE FRESH-WATER LOCHS OF SCOTLAND. 231 



THE LOCHS OF SHETLAND. 



THE Shetland Islands (see Index Map, Fig. 25) are very different in 

 their physical features from the neighbouring group of the Orkneys. In 

 place of the tame undulating surface of Orkney, the Shetlands, though not 

 higher, are more rugged and more varied. High rocky ridges are separated 

 by deep valleys, both running north and south. The more varied surface 

 gives rise to a greater diversity in the lochs. Though many are very 

 shallow, there is not the unvarying flat-bottomed character of the Orkney 

 lochs, and some are relatively deep. In some parts of Shetland there are 

 numerous lochs clustered together, as in North Uist, in other parts there 

 are few lochs. Of the hundreds of lochs in the islands only thirty-one 

 were surveyed. Though there are many basins in which there are 

 numerous lochs, it never happened that we were able to survey more than 

 two in the same basin, and in so many cases was there only one in the 

 basin sounded that the thirty-one lochs surveyed occupy twenty-four 

 separate basins. The area drained by all the lochs surveyed in the islands 

 is just about 50 square miles, a very small proportion of the whole land 

 surface. Only eighteen of the lochs have drainage areas of more than a 

 square mile, eight drain more than 2 square miles, four drain more than 

 5 square miles, and the Loch of Cliif, with the most extensive drainage 

 system in Shetland, drains an area of 8J square miles. The combined 

 superficial areas of all the lochs amount to no more than 4 square miles. 

 The longest loch in Shetland, measured in a straight line between the 

 extreme points, is Loch Strom, on the Mainland. Loch Strom has also the 

 greatest superficial area, a little over half a square mile. The largest body 

 of water is, however, Loch Girlsta, which, though inferior both in length 

 and in area to the two lochs, Strom and Cliff, has nearly three times the 

 volume of water of any other loch in Shetland. The volume of water 

 contained in all the lochs of Shetland which were surveyed, amounts to 

 about 1400 millions of cubic feet, which is but little over the volume of 

 Loch Tummel alone, though that loch is scarcely longer than Loch Strom, 

 or broader than Loch Spiggie. 



The lochs of the Mainland of Shetland number probably some hundreds 

 of various sizes. The great majority are insignificant in size, and there is 

 no really large lake in the island. The largest is not 3 miles in length, 

 the deepest is only 74 feet in maximum depth, and none has a superficial 



