SOMERNEW BOOKS. 
THE SILURIAN ROCKS OF BRITAIN. 
Memoirs of the Geological Survey of the United Kingdom: The Silurian 
Rocks of Britain. Vol. I Scotland. By B. N. Pracu, F.B.S., 
A.R.S.M., F.G.S., and JoHNn Horne, F.R.S.E., F.G.S., with Petro- 
logical Chapters and Notes by J. J. H. Teaut, M.A., F.RS., F.G.S. 
Royal 8vo, pp. xvill.+ 749; xxvii. plates, 121 figures in the Text, 
and a coloured Map on the scale of ten miles to the inch. Published 
by order of the Lords Commissioners of H.M. Treasury, 1899. Price 
15s. 
For some reason that has not yet been discovered, the older rocks of Scotland 
appear to have been formed under somewhat different conditions from those 
which prevailed when rocks of the same age were in process of formation in 
other parts of the kingdom. Not only is this the case with regard to their 
original characters, but it is equally so with regard to their subsequent history. 
Nature’s forces appear to have attacked the older rocks of Scotland more 
energetically than has been the case elsewhere ; and, as a consequence, their 
present arrangement is much more difficult to make out than that of those, 
for example, which are in the Lake District. The Cambrian and Pre-Cambrian 
Rocks of Scotland have been deformed, and their order deranged, to an extent 
which is almost without a parallel outside of the Alps ; and even those rocks 
which were formed between the close of the Cambrian period and the com- 
mencement of Devonian times have fared, in this respect, hardly any better 
than their predecessors. Hence the task of deciphering the geological history of 
the Ordovician and Silurian Rocks of Scotland has presented so many 
difficulties that it has repeatedly baffled the efforts of even the ablest 
geologists. It is quite true that each observer who has tried to work out the 
geological structure of these rocks has added something of value to the com- 
mon stock of information ; but it is now obvious to those who look back upon 
the methods of work adopted by these earlier geologists, that most of them had 
gone upon the wrong lines. As a consequence of this fundamental error, our 
knowledge of the succession of geographical events to which these rocks were 
due, proved to be almost as defective as was our knowledge of the sequence of 
biological events of which these rocks contain a record. 
The reason why so many able men failed to read the history of these 
Scottish Ordovician and Silurian strata aright is sufficiently plain to us, now 
that our eyes are opened. It lay in the fact that, for some inexplicable reason, 
it has long been the fashion in Scotland to ignore the fact that geology is quite 
as much concerned with the past history of Life upon the Earth as it is with 
the physical history of the old sediments in which the vestiges of that life have 
been entombed. In the great majority of cases a student has been trained to 
regard the mineral constitution of some rock, let us say, for example, a dyke, 
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