RECENT ADVANCES IN SCIENCE 131 



notes stratigraphical papers will only be mentioned when they 

 deal with points of especial geological interest. 



The Uintacrinus band of the Upper Chalk has been identified 

 by Mr. R. M. Brydone in the Brighton cliffs {Geol. Mag., January 

 1915). 



The Survey Memoir on Sheet 74 of Scotland describes an 

 area of 432 square miles in mid-Strathspey and Strathdearn. 

 The country rock consists mainly of various phases of the 

 Moine Gneiss, which is intruded by three great granite masses, 

 those of the Cairngorm Mountains, the Monadhliath Mountains, 

 and of Strathdearn. These apparently separate intrusions are 

 believed to be continuous under a thin roof of schist, a view 

 supported by the petrographical identity of the granites and 

 the extensive granitisation of the intervening schists. The 

 area presents a magnificent range of glacial phenomena, which 

 are illustrated by the six fine plates that ornament this excellent 

 memoir. 



The first quarter of the year seems to have been unusually 

 prolific in important petrological memoirs. Mr. Sargent (Geol. 

 Mag., January 1915) describes the Penmaenmawr intrusions as 

 " bronzite-porphyrite," thus reviving an old field name which is 

 gradually falling into desuetude as modern petrography gains 

 in precision. To judge from the number of different names 

 given to these rocks by petrographers they must be of puzzling 

 character. To the reviewer it seems that they closely resemble 

 the quartz-dolerites of the great east and west dykes of North 

 Britain and their accompanying intrusions, a conclusion sup- 

 ported by the occasional presence of micropegmatitic material 

 in the ground-mass, and by the great number of light-coloured 

 segregation veins which also carry micropegmatite. 



S. Powers (Jour. Geo/., January to March 191 5) has collected 

 a great number of cases of inclusions in dykes. On the whole 

 these are rare, and are due to the shattering of the fissure-walls 

 by mechanical agencies. Inclusions may rise, sink, or remain 

 stationary when included in the magma. The direction and 

 degree of movement appear to depend as much on the 

 mechanics of intrusion and the accidents of magmatic circula- 

 tion as on the density of the inclusions relative to that of the 

 magma. 



S. R. Capps (Jour. Geol., January and February 191 5) de- 

 scribes excellent examples of pillow-lavas, probably of Mesozoic 



