180 Reviews—The E'pigene Profiles of the Desert. 
V.—Tue Epiczne Prorites or tar Desert. By A. C. Lawson. 
University of California Publications, Bull. Dept. Geol., vol. ix, 
No. 3, pp. 28-48, 1915. 
(| \HE author discusses the effects of arid erosion on an uplifted land 
mass, and explains the origin of the three elements that enter 
into the profile thus evolved—rock slopes having an angle of less 
than 35°, alluvial fans with slopes rarely exceeding 5°, and wide- 
spread plains. The area to which the paper chiefly refers is that of 
the Great Basin, in which wind scour is held to be ‘‘an extremely 
inefficient agent in the evolution of the . . . relief’’. The encroach- 
ment of alluvial embankments on the rocky slopes is attributed to 
mechanical disintegration, while scanty rains and occasional cloud- 
bursts sweep the detritus to lower levels. Ultimately the cycle 
‘culminates in the ‘panfan’—a vast alluvial surface of aggradation 
below which all rock slopes have at last been buried. As corrasion 
and deflation are dismissed as unimportant, the paper must be 
regarded as applying to a particular desert rather than to deserts 
in general. 
VI.—Brisr Noriczs. 
1. Trrasstc Rocks or Wirrat.—Messrs. Greenwood & Travis have 
given us part ii of their paper on the Mineralogical and Chemical 
Constitution of the Triassic Rocks of Wirral. The paper appears, like 
part i, in the Proc. Liverpool Geol. Soc. (xii (2), 161-88, 1915), and 
deals with the chemical side. The authors arrive at the general 
conclusions (1) that the material of the Wirral Trias, as a whole, was 
derived from igneous rocks of a granitoid nature; (2) that the Bunter 
and Keuper differ in the physical conditions of the grains, but agree 
in containing the same minerals; (3) that the Keuper was probably 
derived direct from the disintegration products of an igneous mass; 
and (4) that the Bunter had ‘previously formed part “of an earlier 
arenaceous rock-mass. 
2. A New Mernop in Zoockocrarpay.—The study of geographical 
distribution is so intimately bound up with paleeogeography, and there- 
fore with geology, that we make no apology for directing the attention 
of our readers to an important paper by Mr. R. J. Tillyard, M.A., of 
Hornsby, N.S.W., ‘‘On the Study of Zoogeographical Regions by 
means of Specific Contours’’ (Proc. Linn. Soc. N.S. Wales, vol. xxxix, 
pp. 21-48, pl. i, 1914). Taking a well-defined group, Mr. Tillyard - 
plots down the number of species recorded from all known localities, 
and calls the lines bounding tracts with the same number ‘‘ specific 
contours’’. He illustrates his method by applying it to the dragon- 
flies of Australia, with interesting results. Another paper by 
Mr. Tillyard is a ‘‘ Study of the Odonata of Tasmania in relation to 
the Bassian Isthmus’’, that portion of land which once (but when ?) 
connected Tasmania with the Australian mainland (op. cit., 
vol. xxxvill, pp. 765-78). 
3. Tae Form anv Consritution or tHe Earta.—An interesting 
paper by L. B. Stewart delivered as the Presidential Address to the 
i i ln ll a nee 
