Reviews—Delta Deposits of the Nile. 39 
argument supporting the existence of the asthenosphere, for the 
distribution of the radio-elements in the earth’s crust carries with it 
the deduction that fusion temperatures (under high pressures) can 
only be approached far below the level of compensation, probably 
200 km., or more, below. In keeping with this view, Barrell holds 
on mechanical grounds that the source of igneous activity is well 
within the asthenosphere. Recrystallization, culminating in local 
fusion, is brought about by the gradual contact of the temperature 
curve with the fusion-solution curve, and ‘‘if this is the cause of the 
disappearance of strength, it should be as much as 300 km. deep and 
extend through some hundreds of kilometres”’. The author draws 
a short sketch of the initiation of magmas and their ascent into the 
crust. He supposes that they are of basaltic or andesitic composition, 
though in the opinion of the present writer the possibility of the 
rocks at such depths being wholly of ultra-basic composition is worthy 
of consideration, together with the mechanism of igneous intrusion 
implied by that view. 
Professor Barrell’s papers constitute a valuable and imme 
contribution to terrestrial dynamics, only the fringe of which has 
been touched upon in this brief and therefore inadequate review. 
ArtHur Homes. 
X.—Detra Duposrrs or tHe Nite. 
Tae Suzsor. or Carro. By E. C. Bowpen Surrg. Cairo Sci. 
Journ., Nos. 97 and 98, vol. viii, pp. 289-50, with 3 plates, 1914. 
NE of the most interesting problems connected with the delta 
deposits of the Nile is their evidence on the supposed isostatic 
movements of the area; and Mr. Bowden Smith discusses the 
evidence of many bores under the Nile delta upon the supposed 
subsidence. He quotes Professor Watts to the effect that the old 
soils, one below another, prove conclusively the repeated subsidence 
of the delta, and he remarks that according to other authorities the 
‘low-level deposits at least were laid down beneath the sea when 
it extended southward up the Nile Valley. Mr. Smith states that the 
delta is not composed of an endless succession of interlaced deposits 
of sand and clay; he concludes from the nature of the deep-level 
deposits and their irregular distribution there is reason to believe that 
they were formed by river-action working under conditions similar to 
those that prevail on the surface at the present day. The author 
remarks that the evidence on this question is not conclusive, and that 
some of the deep-level material may be marine, but he holds that 
repeated substances have taken place between long intervals of rest. 
JWG: 
XI.—Doetrer’s Hanpsoox or Mrneratoay.—We recently received 
the fourth part (Dresden and Leipzig: Theodor Steinkopff. Price 
6.50 marks) of the third volume of the comprehensive Handbuch der 
Mineralchemie, edited by Professor C. Doelter, which was issued in 
July, 1914, just before the outbreak of War. It forms the 
penultimate part of the volume, and in its 160 pages deals with the 
