122 Revieivs — Prof. Hosenhusch's MicrophysiogrcipJii/. 



Eeferring to the Flint Implements found at different levels over 

 the whole district, he observes that he is unable to draw a sharp 

 line of demarcation between Palaeolithic and Neolithic forms. 



Turning his attention to the subject of superficial deposits, he 

 devotes the second part of his paper to the Warp and Trail, described 

 by Joshua Trimmer, and the Eev. 0. Fisher (see Geol. Mag. 1867, 

 p. 193) ; and this subject is illustrated with a number of sections 

 showing the superficial disturbances affecting the Trail. To the 

 folds he applies the name "Underplight," reserving the name Trail 

 for the material filling the troughs and hollows. He believes that 

 the folds or Underplight " may have resulted from the heavy 

 pressure of a superincumbent mass of snow on a soil in a condition 

 capable of yielding, and frequently repeated." No doubt many 

 instances of Trail may in this way have been disturbed, for the 

 Trail after all is generally but the relic of a more extensive gravelly 

 accumulation which has been for the most part denuded. Surface 

 disturbances of similar character are produced in strata over which the 

 Chalky Boulder Clay has been accumulated, and are referable 

 to the agent (probably land-ice) which formed it. Mr. J. G. 

 Goodchild also has drawn attention to many instances of surface 

 disturbance in Kent (to whose paper, by-the-bye, no allusion is 

 made by Mr. Spurrell), and he has suggested that they were pro- 

 bably produced in Glacial times (Proc. Geol. Assoc, vol. ix. p. 151). 



la IB "V" I E ^yAT S. 



I. — MiKRosKOPiscHE Physiogkaphie der massigen Gesteinb. 

 Von H. KosENB-uscH. 1 Abtheilung. Zweite gauzlich umgear- 

 beitete Auflage. (Stuttgart, 1886.) [Pp. 416.] 



Microscopic Physiography of the Massive Eocks. By H. 

 EosENBUSCH. Part I. Second edition, completely revised. 



THE appearance of a second edition of Professor Eosenbusch's 

 well-known treatise on the microscopical study of the igneous 

 rocks will be hailed with satisfaction by all workers in petrology. 

 The present instalment is the first part only : the remaining portion, 

 with the plates for the whole work, is to be expected next Easter. 



On the publication of a new edition of a standard work, the reader 

 naturally wishes to note what alterations and additions have been 

 made to the former text ; but the present edition is so completely 

 re-written as to be practically a new work, and important differences 

 of principle, as well as method, render futile any detailed comparison 

 with the original. The chief features of the author's new treatment 

 of the subject are the prominence given to structure and geological 

 mode of occurrence, the suboi'dination to them of pui'ely mineralo- 

 gical characters as a criterion of classification, and the abandonment, 

 to a great extent, of geological age, or assumed age, as an essential 

 character of igneous rocks. It is true that the division into older 

 (Pre-Tertiary) and newer (Post-Cretaceous) groups is retained among 

 the volcanic rocks : but the only reasons assigned for this artificial 



