Reviews—Prof. Hull’s Physical History of the British Isles. 229 
both at home and abroad, and especially of the Coal-measure period 
and of the “Age of Reptiles.” Professor Hull’s restorations, though 
of course more or less ideal, refer not to the landscape: they are 
maps, and as such are essentially based upon fact, and form a most 
useful index to our present knowledge of the subject. As he rightly 
observes, such a series of illustrations could hardly have been carried 
out without the aid of the numerous deep borings, which, especially of 
late years, have furnished so much useful information; nor, need we 
add, without the combined labours of many geologists for a number of 
years. Of these labours those of Prof. Hull himself have done material 
and conspicuous service, not merely by the field-work carried on in 
England, Scotland, and Ireland on behalf of the Geological Survey, 
but in several important memoirs dealing more or less particularly 
with the configuration of the land in past times. 
The author introduces his present subject as the Paleeo-physiography 
of the British Isles, and makes some useful remarks on the general 
principles to be observed in attempting restorations of old sea-margins. 
Thus the method of formation and deposition of strata are pointed out, 
as illustrated by recent researches; and we may mention, by the way, 
that an excellent summary of deep-sea investigation was given by 
Mr. W. H. Hudleston in his first Address to the Geologists’ Associa- 
tion (1881). Therein we learn, from Mr. Murray’s observations, that 
‘‘Eiven the finer materials derived from the wear of the coast, or 
brought to sea by rivers, are deposited almost entirely within two 
hundred miles of land.” The importance of this fact is pointed out by 
Professor Hull, although he states that in some cases the distance is 
much greater, as, for instance, in that of the Amazon, the muddy 
water from which discolours the ocean at the surface for several 
hundred miles, and by the time the mud subsides, it must reach to 
much greater distances. ‘lhus (as he observes) the fact that sediment 
will tend to increase in thickness in the direction of its source, furnishes 
us with a valuable guide for the determination of the directions towards 
which we are to look, for the lands which yielded materials for the 
strata during any special geological period. ‘The evidence furnished 
by coarse and fine sedimentary materials, and by limestones, is duly 
pointed out, and in a manner that will be understood by those not 
versed in the technical language of geologists. The author is careful 
to point out that neither life, nor the deposition of strata, in one place 
or another, has been completely interrupted for a moment, and that 
hence our great divisions, though convenient, are necessarily based on 
local interruptions or changes. 
A chapter on the ‘‘ permanency of continents and oceans”’ leads us 
to consider the view maintained by some naturalists, and lately ex- 
pressed by Dr. A. Geikie, that ‘(he present continental ridges have 
probably always existed in some form, and as a corollary we may infer 
that the present deep ocean basins likewise date from the remotest 
geological antiquity.”? This view at first seems to run counter to that 
stated by Lyell (Principles, Edit. xii. vol. i. p. 260) that ‘It is not 
too much to say that every spot which is now dry land has been sea 
at some former period, and every part of the space now covered by 
the deepest ocean has been land.’’? But Prof. Hull brings forward 
