122 Reviews—Professor Joly’s Radioactivity and Geology. 
RAVIEWwS. 
LAY PTE S 
I.—Rapioactivity anp Grotocy: an Account oF THE INFLUENCE OF 
Raproactive Enrercy on Terrresrrrat History. By J. Jony, 
M.A., Sc.D., F.R.S. 8vo; pp. xi+287. London: A. Constable 
and Co., Ltd., 1909. Price 7s. 6d. 
(J\HE aorelo acme which have followed so rapidly upon the dicayeee 
i} of the wonderful properties of radium have caused something like 
a revolution in more than one branch of physical science. How much 
these new developments concern geologists was first brought home to 
most of us by Professor Joly’s address at the Dublin meeting of the 
British Association in 1908. The yolume before us is an expansion of 
that address. In it the author marshals the results of researches, to 
which he has largely contributed, concerning the distribution of radium 
in igneous rocks, in sediments of different kinds, and in various waters. 
From the results thus brought together he deduces consequences of 
great moment, which are pursued, in successive chapters of the book, 
through all the ramifications of dynamic geology. 
The variety of subjects which are passed in review, and the fact 
that they are presented as parts of an organic whole, make it difficult 
to do justice to Professor Joly’s work in a brief notice. Indeed, it is 
scarcely possible to summarize what is in effect one extended chain of 
arguments resting on numerical data. It makes us see from a new 
point of view the “complex interaction which unites the varied opera- 
tions of inorganic nature. We are familiar, for instance, with the 
conception of a cycle of events: sedimentation leading to gradual 
subsidence of an area under the growing load, the heating of 
the depressed rock-masses causing upheaval and folding, finally 
erosion coming into play, with transportation and renewed sedimenta- 
tion in an area adjacent to the former. Viewed in the light of the 
radium-content of the sediments, this assumes a new aspect. ‘‘ The 
energy . . . is in fact transported with the sediments—the energy 
which determines the place of yielding and upheaval, and ordains 
that the mountain ranges shall stand around the continental borders. 
Sedimentation from this point of view is a convection of energy” 
(chap. v). In the following chapter the author endeavours to trace 
a like relation between the instability of the ocean floor and the radio- 
activity of oceanic deposits. 
In a book treating of a field so wide and so little explored there is 
necessarily much which must be regarded as debatable. That the 
radioactive processes are not controlled by temperature or pressure is 
a thesis so remarkable that we are entitled to ask for very cogent 
evidence of it. Some experimental data bearing on this point are 
cited, but they do not apply to the breaking up of the parent 
uranium, upon which the whole train of transformations depends. 
If we can suppose this process to be checked by rise of temperature, 
Professor Joly’s argument concerning the relation of underground 
temperature to radioactivity will require revision. It will be no 
longer necessary to assume that the heavy element uranium is 
accumulated in the outer layer of the globe, an arrangement which 
the author explains in a manner not very conyincing. 
