568 Revieics — Posetdtz*s Borneo. 



Permian, althougli at pi-esent there are no fossils known from tbese 

 rocks to establish their real position. Above the supposed Permians 

 is a great series of rocks, the lower portion of quai'tzites, succeeded 

 by beds of gypsum, dolomites and dolomitic limestones, and coloured 

 schists. The greater part of this series is considered by the author, 

 on the evidence of fossils, to belong to the Trias, but it probably 

 includes fragments of Liassic and Jurassic rocks which have been 

 caught up and involved in the folds of the older strata. The author 

 attempts to show that the beds of gypsum and the dolomitic lime- 

 stones in this series are merely lateral modifications of the same 

 deposit, so that in some places the gypsum completely replaces the 

 limestones, whilst in others it occurs either in the upper or lower 

 portions of the series. 



Next above the Trias, the Lower Lias is represented by dark 

 limestones usuall}'^ filled with Belemnites, and the Upper Lias by 

 dark schists or shales. The author has traced out a well-marked 

 calcareous breccia in the Lias ; and in the Upper Jurassic also, there 

 is a definite band of brecciated red marbles containing Ammonites 

 and Belemnites of the group of Duvalia. 



The Tertiary rocks in this region consist of Nummulitic limestones 

 and schists, and the existence is proved of a micaceous and quartzitic 

 breccia of the same age, which had previously been considered 

 Triassic. 



In a region so disturbed as the Alps, it must be difficult to dis- 

 tinguish between real and apparent overlap and unconformity ; the 

 author considers, however, that there is evidence of a real overlap 

 in the Permian rocks, though not of great extent; whilst the overlap 

 of the Triassic strata on the other hand appears to have been very 

 extensive. There is also both an overlap and unconformity between 

 the Upper Jurassic and the Triassic limestones near Guillestre and 

 Castellet. The great overlap of the Nummulitic rocks is established 

 by the fact that these rocks rest successively on the Lias, the Triassic 

 limestones, gypsum, and quartzite, and in the Basses-Alpes, to the 

 south of the present region, on Senonian rocks ; thus indicating the 

 existence of mfivements subsequent to the Senonian, for fragments 

 of these latter are present in the earliest Eocene beds. 



The extent and intricacy of the folding and dislocation of this 

 portion of the Alps are very strikingly shown in the various sections 

 figured by the author, and more particularly in the two remarkable 

 photographs (pis. xxv.-xxvi.) accompanying the second paper, 

 which show a natural section of the escarpments of the Nautbrua 

 Valley. 



II. — Borneo : Its Geology and Mineral Eesources. By Dr. 

 Theodor Posewitz. Translated from the German by Dr. F. H. 

 Hatch, F.G.S. (London: Edward Stanford, 1892, pp. 495; 

 with Geological and other Maps.) 



A THREE years' residence in Borneo gave the author an oppor- 

 tunity of becoming acquainted with tlie leading features in the 

 geology of that island ; he has also devoted himself to an exhaustive 



