Chap. I.] ASCENDING PALAEOZOIC SUCCESSION. 
19 
leled with the Lower Silurian by Logan and the American geologists * are 
there based on unfossiliferous slates, limestones, and sandstones, termed 
' Huronian,' which, in their turn, repose on the crystalline rocks named 
' Laurentian,' — thus showing that America offers the same primeval suc- 
cession as Britain. (See above, p. 11, and Frontispiece.) 
The voyages of our bold Arctic navigators and travellers in search of the 
lamented Franklin led to the discovery of many well-known Upper Silurian, 
Devonian, and Carboniferous fossils in limestones amid the polar ice; 
whilst adjacent to the southern end of America, fossil remains, certainly of 
Lower Devonian date, have been collected by Darwin in the Falkland 
Islands. 
In few of those regions, however, with the exception of North America 
(certainly not in the British Isles, where the strata are in many parts much 
obscured by igneous outbursts), is the order so undisturbed as in Scandi- 
navia and European Russia. There the successive primeval deposits 
extend over a large portion of the earth in regular sequence and in an 
unaltered state. Hence, though to the unskilled eye Russia presents only 
monotonous undulations, chiefly covered by mud, sand, and erratic blocks, 
its framework exhibits a clear ascending series. The older sedimentary 
strata, deviating but slightly from horizontality, are overlain by widely 
diffused masses of those Permian rocks which constitute the true termina- 
tion of the long Palaeozoic period. 
The following pages, as before said, will be chiefly devoted to the Silurian 
stages of the primeval formations. They will be illustrated by woodcuts 
representing the most important organic remains, and certain pictorial 
scenes, as well as sections, chiefly taken from my former works. Faithful 
transfers from the original plates of the ' Silurian System ' are also given, 
with the modern nomenclature of the fossils, and with the addition of the 
plates of Corals, so admirably described by my valued friend and coadjutor 
Mr. "W. Lonsdale. 
"Were the next three Palaeozoic groups to be equally elucidated, this 
work would be expanded far beyond the limits to which I must restrict 
it. The younger Palaeozoic (or the Devonian, Carboniferous, and Permian) 
deposits will therefore be only so far dwelt upon as may be sufficient to 
give the student a general view, and stimulate him to acquire a fuller 
acquaintance with them by consulting the various works wherein they are 
circumstantially described. But even the sketch of them given in this volume 
will, it is hoped, suffice to show that, while the contiguous strata of two 
natural groups are intimately linked together by containing species which 
are common to both, the principal fossils of each are certainly peculiar. 
Although few of the mineral changes of the strata can be alluded to, an 
* See particularly the works of James Hall and geologists ; and the recent general maps of North 
Dale Owen ; the Eeports and maps of Logan, the America, by Eogers and Marcou. See also a table 
chief geologist of Canada ; the maps of Lyell, as by Professor Ramsay in Chapter XVIII. 
compiled from the works of the United- States 
c2 
