In Silurian and Devonian Epochs 115 



sils, the absence of plants and animals that would suggest 

 freshwater conditions, all conspire to stamp them. 



But probably contemporaneous with these, or at times 

 intercalated between them, as seems particularly to be true 

 of those in North America to be noted below, are extensive 

 and thick masses of rock, which from their predominantly 

 red color and high ferruginous content, were early named 

 "the Old Red Sandstone." These are largely confined — in 

 their known exposure — to Wales, to North and East Ire- 

 land, are very extensively developed in Scotland and Rus- 

 sia, and they appear also in Norway. Their great develop- 

 ment in North America will be referred to later. Studied 

 throughout Europe in succession by Murchison, Fleming, 

 Godwin-Austen, Ramsay, Hugh Miller, Mitchell, Agassiz, 

 Powrie, Geikie, Peach, Flett and many others, the strata 

 seemed to be divided into at least two or even three divi- 

 sions that were mainly characterized by their diverse fish 

 remains. 



Geikie says regarding them (7:1007) : "The Old Red 

 Sandstone of Britain, according to the author's researches, 

 consists of two subdivisions, the lower of which passes 

 down conformably into the Upper Silurian deposits, the 

 upper shading off in the same manner into the base of 

 the Carboniferous system, while they are separated from 

 each other by an unconformability." This author made 

 a very detailed study of the entire system throughout the 

 British Isles, and alike in special papers ( (5^ : 3 1 2 ; 2j : 345 ) 

 as well as in his exhaustive work "Ancient Volcanoes of 

 Great Britain" (70) has developed the view that the 

 rocks of both lower and upper divisions were enormous 

 lacustrine deposits, that occasionally reached a maximum 

 thickness of 30,000 feet. These were laid down in a 

 group of freshwaters which he named Lakes Caledonia, 

 Orcadie, Cheviot, and Lome, and of them he says: "There 

 is sufficient diversity of lithological and palaeontological 

 characters to show that these several areas were on the 

 whole distinct basins, separated from each other and from 

 the sea. The interval between the Lower and Upper Old 

 Red Sandstones was so protracted, and the geographical 

 changes accomplished during it were so extensive, that the 



