200 peteoiogt". 



Jurassic, Cretaceous, Tertiary, and Drift. He recognizes three classes 

 of constituents : — Clastic materials, or fine rolled fragments of minerals 

 and rocks ; Crystalline constituents, not developed by metamorphism, 

 but deposited at the time of formation of the rock (some of these are 

 figured) ; Organic constituents, chiefly remains of foraminifera. Con- 

 cludes that although crystalline constitutents are not confined to the 

 Pala30zoic slates, the proportion of such constituents diminishes with 

 the age of the rock ; a Mesozoic shale, for example, contains less crys- 

 talline matter and more mechanically-formed materials than does a 

 similar Palaeozoic rock. P. W. K. 



Cronqtjist, a. W. Jemforande undersokning af eldfasta leror fran 

 Stabbarps stenkolsschakt i Skane. [Comparative analyses of fire- 

 clays from the shaft of the Stabbarp Coal-mine in Scania.] Geol. 

 foren. Stockholm Porhandl. bdt. ii. pp. 58-70, 1 fig. in text. 

 The analyses tend to show that the clays, which are Liassic, can be 

 favourably compared with the best foreign fire-clays. A great number 

 of analyses of various clays are given. G. A. L. 



Cfery, J. Stalagmitic Deposits. Geol. Mag. dec. 2, vol. i. p. 191. 

 Describes a deposit at Boltsburn, Durham, 18 inches long, 10 

 broad, and | inch thick, which has been formed in fifteen years. 



Dana, E. S. Abstract of a paper on the Trap Kocks of the Connec- 

 ticut Yalley. (Eead to Amer. Assoc. 1874.) Amer. Journ. ser. 

 3, vol. viii. pp. 390-392. 

 This trap forms part of a system of dykes through the Secondary 

 Sandstone of N'ova Scotia, New Jersey, Pennsylvania, and North Caro- 

 lina, but nowhere so well shown or in such numbers as in the Con- 

 necticut valley. The author finds that "the trap which has come up 

 through the older crystalline roclcs is most of all free from hydrous mine- 

 rals or any evidence of alteration, its grains having a fresh, vitreous 

 look on the fracture." A strongly amygdaloidal trap occurs in the 

 same dykes as the massive variety. G. A. L. 



Dana, J. D. [Connecticut Traps.] Zeitsch. deutsch. geol. Ges. 

 Bd. xxvi. Heft 4, pp. 939, 940. 



Letter stating that the writer's son had prepared about 150 sections 

 of " trap " rocks from Connecticut, and had found them to consist of 

 dolerite and diabase. The trap-dykes cutting through crystalline rocks 

 are true dolerites, and the traps on the western border of the Connec- 

 ticut valley are also free from chlorite, whilst those of the middle and 

 eastern Triassic districts are diabase ; the further to the east the 

 richer are they in chlorite. P. W. P. 



Dathe, J. P. E. Mikroskopische TJntersuchungen uber Diabase. 



[Microscopic Investigations on Diabase.] Zeitsch. deutsch. geol. 



Gessel. Bd. xxvi. Heft 1, p. 1. 

 Gives a list of the principal Saxon localities of diabase, a detailed 

 description of the minerals which enter into its composition, and an 



