Recieios — Prof. Stefani — Eruptive Rocks of the Apennines. 323 

 ZEa IE "V I IE W S. 



I. — Le rooce ertjttive dell' Eocene superiore nell' Apenxino. 

 By Prof, de Carlo Stefani. Boll. Soc. geol. Ital. VIII. No. 2, 

 1889. 



n^HE Eocene eruptive rocks of Northern Italy have already acquired 

 I a somewhat extensive literature. The last addition to this is 

 the above-cited memoir, which fully sustains its author's reputation 

 for viewing petrological subjects from an advanced standpoint. 

 The memoir is therefore of value, not only as a contribution to the 

 study of some local rocks, but as a pronouncement on the part of a 

 leading Italian geologist on some of the broader geological problems 

 connected with them. English geologists especially will be interested 

 in the expression of such views as "it is wrong to give distinct 

 names to rocks in their altered conditions" (p. 262), or that "from 

 the point of view of lithology, it may be affirmed, in contradiction, 

 to the teaching of my masters, that the ancient eruptive rocks are 

 identical with the modern" (p. 262). Prof. Stefani has previously 

 expressed similar views, but they have probably never before 

 been so definitely asserted by any Italian geologist. 



The memoir commences with a useful bibliography, and is divided 

 into nine sections. The first deals with the nature, mode of origin, 

 and correlation of the beds with which the igneous rocks are asso- 

 ciated : a full list of fossils is quoted, and a short sketch given of 

 the work by which the old view of the submarine volcanic age of 

 the deposits has been disproved. The author maintains instead that 

 they are really normal deep-sea deposits. 



The igneous rocks are described in the next five sections ; their 

 origin discussed in the seventh; the eighth and ninth are devoted to 

 their stratigraphical relations and distribution, and a summary of 

 the author's opinions concludes the memoh\ 



§ 2. The Peridotites. — The most important of these is a mixture 

 of olivine and enstatite, for which Wadsworth's name of saxonite, 

 though admittedly a misnomer, is preferred to the later name of 

 " harzburgite " (Rosenbusch). The occasional presence of diallnge 

 as at Levanto (Bonney), and at Pria Borgheise (Mattirolo), indicates 

 an approach to lherzolite ; but the author regards the diallage in 

 these cases as always accessory, and hence declines to accept the 

 rocks as true lherzolites, though Bosenbusch has so named the rock 

 of the latter locality. In other cases the presence of augite suggests 

 a passage to picrite (of Rosenbusch), while in places the scarcity 

 of enstatite leaves the rock as a kind of " dunite." The author 

 denies the occurrence of " wehrlite " on Monte Prato. 



The serpentines have always, according to Prof. Stefani, resulted 

 from the alteration of saxonite. In supporting this conclusion he 

 dismisses the following hypotheses of the formation of serpentine : 

 (1) from argillaceous schist, advanced by Achiardi in 1874, a view 

 based on superficial resemblances ; (2) from diallage, as urged by 

 Berwerth for that of Bosignano, in consequence of his having 



