22 ON CHANGES IN THE DISPOSITION 



ritime forests, extends the well-known marshy tracts by 

 which so many of these shores are skirted; often co- 

 vering, as in Borneo., spaces almost incredible, and with 

 effects but too well known. 



The last geographical effect of this nature which I 

 need notice, is the formation of fresh water lakes on the 

 margin of the sea ; being an occasional result of that 

 process which fills a bay by the production of a spit or 

 bar. The descent of the terrestrial alluvia being checked 

 by the tide, a bank is produced, which gradually raising 

 itself above the waters, becomes dry land ; continu- 

 ing to receive accessions of materials on the interior 

 side, and often on both. If the entrance of a powerful 

 river, united to a peculiar form in the shore, determines 

 a rapid increase of the land at the aperture, its channel 

 may at length become so narrowed and prolonged 

 through the bar, that the further entrance of the sea is 

 checked ; and thus a fresh water lake is the result. 

 This occurs in the Crimea, according to Pallas, and in 

 the Gulf of Mexico ; while, in our own island, the 

 whole process can be seen, from the commencement 

 to the termination, in different places. The long trans- 

 verse spits of the Gare loch and Loch Fyne are exam- 

 ples of the first stage : at the Connel ferry and Balahu- 

 lish, these spits have become plains ; leaving, at the 

 latter place in particular, but a narrow passage for the 

 water : while, whether the ultimate result will ever 

 happen in these places or not, it has taken place in a 

 small lake near Cape Rath, now occupying what was 

 once a salt bay. 



Of antient unknown Currents 



Whatever imagined facility may be afforded by such 

 currents in explaining geological phenomena, it is an 

 hypothesis which has been rendered repugnant by its 



