CRUISE IN LOCH FYNE, JUNE, 1899. 375 



but it has more probably been formed by the action of tides 

 and currents. 



In the New Statistical Account (1844) the minister of the parish 

 of Glassary writes — " There is a remarkable bank formed of sand 

 and debris from the hills on each side of Lochfyne at Ottar. 

 This bank, with the other depositions by which the bed of Loch- 

 fyne must necessarily be raised in its level from year to year by 

 the disintegration of rocks, the carrying away of banks, etc., may 

 possibly effect great changes upon the character of the loch above 

 Ottar on some future day, by obstructing the ingress of the tide 

 and converting the upper portion into a fresh -water lake with its 

 river entering the sea; and would it not be worthy of the heritors 

 to take some measure of making such observations on each side 

 of the Ottar, as may be necessary to ascertain the rate of increase 

 of this bank, if any ; whether there be a tendency to the forma- 

 tion of a similar bank down on the north side, etc. 1" 



The run of the current is, we expect, sufficient to keep the 

 channel open, but such observations would be of considerable 

 scientific interest. 



The geological structure of the rocks in the neighbourhood of 

 Loch Fyne is very complex. No organic remains have yet been 

 found in them. Their age is not known; they may be Lower 

 Silurian, Cambrian, or even Pre-Cambrian. Those in the Cowal 

 district have been described in the memoir of the Geological 

 Survey, already referred to, published in 1897. 



Most of the rocks are evidently of sedimentary origin, but 

 since they were deposited in the seas or lakes of remote 

 times they have undergone great changes, whereby their original 

 structure has been completely altered, and they now present a 

 highly crystalline appearance. Even the igneous rocks appar- 

 ently intruded into them, and if so, newer than the sedimentary 

 rocks, have been metamorphosed, with the exception of the mica- 

 traps, lamprophyres, and dykes of probably late Carboniferous 

 and Tertiary ages. This metamorphism has perhaps been caused 

 by earth movements on a large scale, whereby the strata forming 

 the crust of the earth have been folded, twisted, and crumpled. 

 These movements have occurred more than once, and the 

 repeated foldings have produced new structures in the rocks. 

 The original lines of bedding have in many cases been almost or 



