lo: 



NA TURE 



[July 22, 1909 



the last two minerals, the second of which is often 

 fairly idiomorphic. It is, in fact, a variety of 

 quar'tz-diorite, for which some petrographers use the 

 name. Enclosures of a darker, more basic rock are 

 not unfrequent, which in some cases much resemble 

 included fragments, but in others may have a con- 

 cretionary origin. The tonalite is cut by dykes of a 

 more aplitic character, and apophyses from it pene- 

 trate the neighbouring sedimentary rocks. The per- 

 centage of silica is rather lower than in an average 

 granite, that of ferro-magnesian constituents is 

 higher, while in the alkalies the soda much exceeds 

 the potash. The monzonite of the Fassathal differs 

 from it in being poorer in silica and richer in alkalies; 

 the granite of that valley and of the Cima d'Asta 

 exceeds it in both respects; but, as we see from the 

 neighbourhood of Predazzo, these early Mesozoic ejec- 

 tions indicate much differentiation of any original 

 magma. But for these interesting questions it is 

 enough to refer to Prof. Brogger's classic memoir ' 

 on that district. 



If this tonalite massif represents the supply basin 

 to one or more volcanic orifices, all traces of the 

 latter have completely disappeared. The blood-red 

 "porphyries," so characteristic of abroad region east 

 of the -Adige, above and below Dozen, can also be seen 

 west of that river, at no great distance from the 

 Adamello, and can be traced south of it to beyond the 

 Sesia. These were erupted in Permian times, but the 

 tonalite, like those other holocrystalline masses already 

 mentioned, is later than most of the Trias. On that 

 point evidence has been accumulating since 1846, but 

 it is made more than ever certain by Dr. Salomon's 

 exhaustive examination of the relations of the tonalite 

 and the various stages of that system from the 

 VVerfener Schichten (Bunter) to the Haupt Dolomit 

 (lower part of the Rhsetic). The usual proofs of in- 

 trusion can be seen in many places, and a zone of 

 contact metamorphism traced for a considerable dis- 

 tance outwards from the margin of the invading rock. 

 It can also be seen breaking into Permian sediments 

 and into the older crystalline schists. 



These schists Dr. Salomon divides into three groups : 

 the Edolo .Schiefer, the Rendena Schiefer, and the 

 Tonale Schiefer. The first, which occur on the north 

 and in the northern part of the west of the Adamello 

 massif, are said to be phyllites, sometimes anthracitic, 

 with quartzose-banded phyllites and quartzites ; the 

 second, consisting of phyllitic gneisses and mica 

 schists, occur occasionally on the west, but are more 

 developed on the east ; and the third, specially char- 

 acterised by bands of saccharoidal marble, often rich 

 in silicates, and associated in one part with a zone 

 of augen gneisses, occur on the north, on the other 

 side of the Edolo Schiefer. Dr. Salomon regards the 

 Rendena Schiefer as early Cambrian or late Archaean, 

 but refers some of the Tonale Schiefer to the Meso- 

 zoic, considering the marbles to be infolded Triassic 

 limestones, metamorphosed by intense pressure. It 

 may seem presumptuous for one who has merely 

 traversed this district, and that not at all recently, 

 to express any difference of opinion, but, as Dr. Salo- 

 mon supports his views by references to other parts 

 of the Alps which the present writer has carefully and 

 continuously studied, he has no hesitation in say- 

 ing that the identification of those Alpine marbles with 

 the acknowledged Triassic limestones is very like that 

 of Monmouth and Macedon, and that the asserted 

 Mesozoic age of the crystalline schists, to which most 

 of the so-called phyllites belong, and with which these 

 marbles are associated, is supported by no better 

 evidence than mistakes in elementary mineralogy and 

 the neglect of important facts, such as the presence of 



^ " Die Eruptionsfolge der iriadischen Eruptivgestcine bei Predazzo," 1895. 

 NO. 2073, VOL. 81] 



fragments of those crystalline schists in indubitable 

 Triassic rock. So we venture to think that the last 

 word has not yet been said on the subdivisions and 

 the ages of these crystalline schists. 



As dolomitic limestone occurs in the neighbourhood 

 of the Adamello, the author discusses the relation of 

 these rocks to coral reefs. Here we are surprised 

 at not finding any direct reference to the Royal 

 Society's memoir on the borings at Funafuti, and the 

 author is apparently satisfied with the following 

 quotation (p. 417) : — " Die Bohrung auf Funafuti 

 erscheint in demselten Licht ; die dort erreichte grosse 

 Dicke wurde wahrscheinlich in der Grunlage einer 

 alten Kalksteines erreicht, so dass die erlangten Resul- 

 tate keinesweg die Annahme der Senkungstheorie 

 ndtig machen." We can only suppose that Dr. Salo- 

 mon has never seen the conclusion of Dr. C J. Hinde's 

 study of the cores (Memoir, p. 334) : — " The evidence 

 appears to me to indicate a continuous formation of 

 reef rock, without any abrupt break, from the depth 

 of 1 1 14 feet to the present time "; while Prof. J. W. 

 Judd (p. 175), after stating that specimens of Tertiary 

 limestones from reefs in Indian and Pacific seas had 

 been carefully studied for purposes of comparison, 

 expressly states : — " The same recent forms of fora- 

 minifera, corals and other organisms occur from the 

 top to the bottom of the series of cores. On this point 

 the evidence appears to be conclusive, and we are 

 justified in stating that no basis of old Tertiary lime- 

 stone was reached in the deep boring at Funafuti." 



But these two defects, for such we deem them, do 

 not blind us to the many merits and great value of 

 this memoir. The facts will remain, even if, in a few 

 cases, Dr. Salomon's interpretation of them be ulti- 

 mately set aside. The book is the outcome of years of 

 patient toil, and, when completed by the petrographical 

 and palEeontological studies of his collections, will be 

 a permanent monument to his scientific energy, zeal; 

 and acumen. T. G. B. 



TIDAL PROBLEMS^ 



np HE authors of the planetesimal theory have in 

 ■*• this volume made a further important contribu- 

 tion to the discussion of the problems of cosmogony. 

 In their endeavours to establish their own theory on a 

 sound footing, much work has necessarily to be done 

 in the way of criticising earlier theories. The 

 classical nebular hypothesis of Laplace has already 

 been discussed in a series of papers by Profs. 

 Chamberlin and Moulton, and found wanting in many 

 respects. To them in part is due the general abandon- 

 ment of this hypothesis in anything like its original 

 form by most astronomers of the present day. The 

 present volume of papers is directed mainly against 

 the tidal theories developed by Sir George Darwin, 

 and more particularly against the view that at some 

 far-distant epoch the moon separated from the earth. 

 Prof. Chamberlin 's paper on " The Former Rates of 

 the Earth's Rotation " opens with an attack on the 

 theory of centrifugal separation of the heavenly bodies. 

 We are compelled to admit the force of many of his 

 criticisms with regard to the separation of the planets 

 from a parent sun, but the similar criticisms levelled 

 against the formation of the planetary sub-systems 

 are lacking in w^eight. In particular, the argument 

 from a comparison of the present orbit of Phobos 

 with the ring system of Saturn fails if a change in 

 the dimensions of the orbit of Phobos, assumed 

 negligible, is allowed for. Also the mere statement 



1 "The Tidal and other Problems." By Profs. T. C. Chamberlin, 

 F. Tv. Moulton. and others. Pp. iv-^264. (\\'ashington : Carnegie 

 Institution, 1909 ) 



