and Littoral Manganese Nodules 167 



from Loch Fyne, one of the most important arms of the Firth 

 of Clyde. They are from a lump of mud which came up on the 

 fluke of the deep-sea kedge-anchor of the steam yacht " Mallard" 

 after a series of temperature observations in the deepest part 

 of the loch on the 2ist September 1878. 



The Firth of Clyde is the name given to the most remarkable 

 group of fiord-like channels and sea lochs in the British Islands. 

 They form a compact basin or depression, and it has been named 

 after the principal stream which empties itself into it the river 

 Clyde. If we draw a straight line through the Craig of Ailsa 

 and Sanda Island, at the extremity of the Peninsula of Cantyre, 

 -hall have delineated the Firth seawards, and a line of 

 soundings along this line discloses an almost perfectly uniform 

 depth of water of from 23 to 25 fathoms. If we run a line of 

 soundings at right angles to this line, we shall find the water 

 deepening as we retire from the line whether we go northwards 



f.U* 



Loch Fyne. Section I. Cantyre to Cowal. 



or southwards. If we go northwards we find the depth increase 

 gradually and steadily as we pass the Island of Arran, whether 

 by the main <hannel on the east, or by Kilbrennan Sound on 

 the west ; so that Arran stands, as it were, on an inclined plane 

 sloping northwards from the mouth of the Firth, attaining a 

 depth of 90 fathoms off the N.E. point of the island, and con- 

 tinuing as a deep trough into Loch Fyne, with a maximum 

 depth of 104 fathoms 1 close to Skate Island and about three 

 >m the entrance of tin- lo< h. ThN deep trough only 

 occupies a portion of the width of the loch, as is shown by the 

 nd section \t fa month the loch measures four 

 n.rnti. .,1 miles arros S but the \vidth of the portion >f it over 

 5ofath< ; t h is only one mile. Both the loch, as a whole, 



See Map. 



