66 
perienced it is of profound interest from be- 
ginning to end. TEHach geological age is made a 
chapter, or series of chapters, by itself and is 
prefaced with a short, clear exposition of the 
general geology of that age as represented in 
the British formations, thus preparing the way 
to the easiest understanding of the relations of 
the volcanics to the geology at large. The first 
one will be of deep interest to all geologists, and 
to many it will be the most fascinating. For it 
treats of the pre-Cambrian rocks and the mys- 
tery of the ‘fundamental complex.’ In a few 
paragraphs he sketches in outline the state of 
knowledge of the. rocks which underlie the 
oldest known sediments of Britain. Here, at 
the uttermost bounds of geological knowledge 
and in the dim light of the earliest known order 
of things, we find remnants of volcanic action. 
The admirable studies of Teall among the 
Lewisian or ‘fundamental’ gneisses of Murchi- 
son, exposed in the northwest of Scotland and 
in the Hebrides, leave little doubt that the great 
bulk of them are plutonic igneous rocks. They 
differ in no essential respect from those deeply 
buried bosses or intrusions of later ages which 
are known to be connected with surface erup- 
tions and constitute the subterranean portions 
of the outflowing masses. But beds clearly 
contemporaneous and erupted at the surface 
have nowhere been identified, and interbedded 
clastic voleanic formations are also absent. On 
the other hand,the Archzean complex is traversed 
by innumerable dykes, which are certainly 
older than the oldest rocks which overlie the 
complex, and their volcanic nature is unmis- 
takable. It is interesting to compare this with 
the conclusions reached by American geologists 
in the ‘basement complex’ of Canada and Lake 
Superior, where the facts are of the same na- 
ture and the conclusions are the same, except 
that surface eruptions both massive and clastic 
are recognized in abundance. 
Sir Archibald still retains the name ‘ Lewis- 
jan gneiss’ as originally given by Murchison. 
Why have our geologists been so shy of the 
good old name, Laurentian, given by Logan? 
Certainly a rose by any other name will smell 
as sweet, but what is the use of the other name ? 
_ The extreme caution and candor of Irving (R. 
8.) were lovable, but they did not call fora new 
SCIENCE. 
_eruptions have been proven. 
[N. 8. Vox. VI. No. 132° 
one. The old one would have misled nobody 
unless the true spirit of geology were not in 
him. All needful reservations geologists will 
make for themselves. 
In the same chapter the reader is carried up 
into the vast pre-Cambrian formations which 
overlie the Lewisian, from which they are 
divided by the great unconformity, probably the 
greatest in all geological time, and to the first 
great series the name of Torridon sandstones 
is given. They abound in dykes, intrusive 
sheets (or ‘sills’) and bosses, but no surface 
Higher still after 
another great unconformity is a vast succession 
of crystalline schists (provisionally named 
Dalradian) whose age is not yet determined, 
but which seem in part at least to be pre-Cam- 
brian. They too abound in eruptives and their 
general character suggests our own Algonkian 
rocks. It is obviously impossible here to note in 
detail the substance of the long series of chap- 
ters which carry the reader from the Archean 
to the close of the Paleozoic. Only the most 
general summary can be given. And yet to 
pass thus cursorily over the many chapters re- 
lating to the eruptive masses of the Cambrian, 
the Silurian, the Old Red Sandstone, and, above 
all, the long series of chapters devoted to the 
Carboniferous, with all their wealth of ma- 
terial wrought out in such a masterly way, 
seems unappreciative. We are presented with 
an immensely long vista of volcanic action, be- 
ginning with the earliest epoch of which we 
have any knowledge and extending down to 
the close of the Paleozoic, manifesting itself 
in all that succession of ages. But the more 
ancient they are the more profoundly have the 
erupted materials been changed or modified by 
metamorphic action and disturbed by repeated 
earth movements with dislocations and distor- 
tions of the strata, so that the determination of 
their true volcanic nature has required many 
years of labor by hundreds of earnest workers 
in the field and laboratory and with the micro- 
scope. The result of this labor now seems well 
assured, not only in Britian, but in all other 
countries where geologic research is diligently 
prosecuted. One grand result of it is the con- 
clusion that voleanic action has been the same 
in all ages. And when our thoughts reach 
