222 BATHYMETRICAL SUKVET OF 



THE LOCHS OF OEKNEY. 



THE Mainland of Orkney possesses many fine lochs. The land surface 

 consists of a series of low dark- topped hills, none reaching 1000 feet in 

 height, between which are broad stretches of level or gently undulating 

 moorland, now in great part under cultivation. In correspondence with 

 this conformation of the land, and the absence of narrow valleys, the lochs 

 occupying the hollows are all relatively broad, and they are without excep- 

 tion shallow and flat-bottomed. The two very large bodies of water, the 

 Lochs of Stenness and Harray, which ramify into the very heart of the 

 island, are subject to the influence of the tides, though their level is but 

 slightly affected. 



In the mountainous islands of Hoy and Rousay there are narrow valley 

 lochs of greater depth than any on the Mainland. On the other islands of 

 the group, which are quite low, there are only a few unimportant lochs, 

 which were not surveyed. In the three islands visited (see Index Map, Fig. 

 24) fourteen lochs were surveyed. The largest, in every respect, is the Loch 

 of Harray ; the Loch of Stenness is little inferior in size, but all the others are 

 much smaller. The deepest loch on the Mainland, the Loch of Stenness, 

 17 feet in depth, is slightly exceeded in depth by the Muckle Water in 

 Rousay, but by far the deepest loch surveyed is the little Hoglinns Water 

 in Hoy, which is 57 feet deep. The combined superficial areas of all the 

 lochs surveyed amounts to 10 square miles, and the area draining into 

 these lochs exceeds 90 square miles. 



The Island of Hoy is the most mountainous of the Orkneys. With the 

 exception of the Peninsula of South Walls, joined to the main island 

 merely by a causeway, the island consists of one mountainous mass, rising 

 from south to north, where it culminates in three peaks of over 1300 feet 

 in height, separated by deep glens which cut right across the island. The 

 central peak, the Ward hill, 1564 feet in height/ is the highest point in 

 Orkney, and even exceeds the highest hill in Shetland (Ronas hill, 

 1475 feet) by nearly 100 feet. On the southern slope of the island are 

 several lochs, which, from their highland situation, might be expected to 

 be deeper than the lochs in the plains of Pomona. That this is in fact the 

 case can be definitely stated of one little loch, the Hoglinns Water, the 

 survey of which, begun by the Lake Survey, was completed by Mr. William 

 Mar wick, who found a depth of 57 feet. The largest loch in Hoy, the 

 Heldale Water, about a mile in length, was not suryeyed. 



