14 KEPORT— 1880. 



it is probable that the cis-Himalayan palaeozoic rocks are in great part of 

 fresb- water origin, and that the present crystalline axis of the Western 

 Himalayas approximately coincides with the shore of the ancient palseozoic 

 continent, of which the Indian peninsula formed a portion.' The Ea-ol 

 rocks are classed broadly with ' Permian and Carboniferous ' deposits, 

 but the Blaini beds are doubtfully considered to belong to Upper Silurian 

 strata. If this point be by-and-by established, this is the earliest known 

 occurrence of fresh-water strata in any of the more ancient palseozoic 

 formations. 



It is a fact worthy of notice that the colour of the strata formed in old 

 lakes (whether fresh or salt) of pateozoic and mesozoic ago is apt to be 

 red : a circumstance due to the fact that each little grain of sand or mud 

 is usually coated with a very thin pellicle of peroxide of iron. Whether 

 or not the red and purple Cambrian rocks ' may not be partly of fresh- 

 water origin, is a question that I think no one but myself has raised.^ 



There is, however, in my opinion, no doubt with regard to the fresh- 

 water origin of the Old Red Sandstone, as distinct from the contem- 

 poraneous marine deposits of the Devonian strata. This idea was first 

 started by that distinguished geologist. Doctor Fleming, of Edinburgh, 

 followed by Mr. Godwin-Austen, who, from the absence of marine shells 

 and the nature of the fossil fishes in these strata, inferred that they 

 were deposited, not in the sea, as had always been asserted, but in a great 

 f resh-water lake or in a series of lakes. In this opinion I have for many 

 years agreed, for the nearest analogies of the fish are, according to Huxley, 

 the Polypterus of African rivers, the Ceratodus of Australia, and in less 

 degTce the Lepidosteus of North America. The truth of the supposition 

 that the Old Red Sandstone was deposited in fresh water, is further borne 

 out by the occurrence of a fresh-water shell, Anodonta JuJcesii, and of ferns 

 in the Upper Old Red Sandstone in Ireland ; and the same shell is found 

 at Dura Den in Scotland, while in Caithness, along with numerous fishes, 

 there occurs the small bivalve crustacean Estheria Murchisonise. 



I think it more than probable that the red series of rocks that form the 

 Catskill Mountains of North America, (and with which I am personally 

 acquainted) were formed in the same manner as the Old Red Sandstones 

 of Britain ; for excepting in one or two minor interstratifications, they 

 contain no relics of marine life, while 'the fossil fishes of the Catskill 

 beds, according to Dr. Newberry, appear to represent closely those of the 

 British Old Red Sandstone.' (Dana.) 



The Devonian rocks of Russia, according to the late Sir Roderick 

 Murchison, consist of two distinct types, viz, Devonian strata identical in 

 general character with those in Devonshire and in various parts of the 



^ By Cambrian, I mean only the 7'ed and purple rocks of Wales, England, Scot- 

 land, and Ireland, older than the Menevian beds, or any later division of the Silurian 

 strata, that may chance to rest upon them. 



" ' On the Red Eocks of England of older date than the Trias.' Jour. Geol. Soc. 

 1871, vol. 28. 



