CLYDE SEA AREA. 649 



describe its configuration at greater length. The length along the axis from the Otter 

 Spit to the head is 26 miles, but a straight N.E. line, joining the middle of the channel 

 off Otter with the head, measures only 24^ miles. The width at Otter is If miles at 

 high water, but only about § at low tide, when the maximum depth on the barrier is 

 15 fathoms. The loch varies in width irregularly from § to 1 mile as far as Inveraray, 

 but in the last 6 miles diminishes uniformly to less than \ mile. The Arran Basin has a 

 due north direction at the point where Loch Fyne joins it, and a short branch or bay of 

 shallow water — Loch Gilp— reaches further in that direction. Loch Fyne runs from the 

 end of the Central Arran Basin for 9| miles N.E. by N. ; then, from a contraction at 

 Crarae, N.E. by E. f E. for 4 miles to Kenmore ; thence, curving once more, N.E. by N. 

 \ N., 4-| miles to Inveraray, where the shallow bay of Loch Shira, connected by a short 

 tidal river to the fresh Dubh Loch, runs on in the same direction. Here Loch Fyne 

 swerves to N.E. by E. \ E., its final direction, which is held for 6^ miles to the head. 

 Loch Fyne is divided into two distinct hollows, or subsidiary basins (section 3, Plate I.). 

 From Otter Spit, where the depth is 15 fathoms in mid-channel, to the islands forming 

 Minard Narrows, where there are two narrow and shallow passages, is a distance of 

 7\ miles, and the depth increases uniformly from both ends to the centre, where there is 

 a line of soundings of from 30 to 32 fathoms. This may be termed the Gortans Basin, 

 after a headland which projects from the eastern shore. It is a sort of trap, with double 

 bars retarding the access of sea water to the depths of the Upper Basin. The Upper Basin, 

 beginning at Minard Narrows, deepens at first somewhat irregularly, but then sinks 

 abruptly to a depth of nearly 80 fathoms off Pennimore Point, 4^ miles from Minard ; then 

 rises gradually until, off Inveraray, the slope becomes much steeper, and the upper end of 

 the loch shallows rapidly. Sections 18, Plate IX., show on a natural scale the trans- 

 verse profile at three important points in Loch Fyne. The coast on both sides of the 

 Gortans Basin slopes more gradually than on any of the other lochs except the Gareloch, 

 but the upper 5 miles is invested by a close, steep, and lofty mountain-wall. The land 

 area draining to Loch Fyne is disproportionately small, as the valley of the Ruel on the 

 east and that of the Add on the west run parallel to the main depression collecting the 

 streams, and conveying them to Loch Eidun and Loch Crinan respectively. Near the 

 head the Aray, Shira, and Fyne are the largest rivers which enter, and these are all short, 

 and carry much water only after rain. The water area of Loch Fyne is 28^ square miles, 

 and the land draining into it is 188 square miles, mainly to the north-east. The total 

 volume at low water is very nearly 0*5 cubic sea mile, and at high tide 0'029 in addition. 

 The mean depth is 22-^ fathoms, and the average depth along the axis 40^ fathoms at 

 low tide. 



The peninsula of Cowal, which stretches between the roughly-parallel inlets of the 

 Arran Basin with Loch Fyne, and the Dunoon Basin with Loch Long, is trenched by a 

 series of transverse valleys, most of which are occupied by deep loch basins, and these have 

 a general trend to N.N.W. The south-east margin of the Arran Basin- Loch Fyne depres- 

 sion from Ardlamont Point to Glen Fyne is edged with a line of high ground, gradually 



VOL. XXXVI. PART III. (NO. 23). 5 F 



