THE FKESH-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 neigh uring group of the Orkneys. In 
place of the tame undulating surface of Or kney, 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 Hist, 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 60 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 Cliff, with the most extensive drainage 
system in Shetland, drains an area of 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 poiffts, 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 
