RECENT ADVANCES IN SCIENCE 33 



fades of felspar-basalts as " felspathic picrite," an ill-chosen 

 name. A neighbouring rock distinguished by the predomin- 

 ance of pyroxene over olivine is called ankaramite, and the 

 melanocratic fancies of nepheline-basalt ankaratrite, both terms 

 being derived from Madagascan localities. This is a step in 

 the right direction, as terms like " basalt " are fast becoming use- 

 less owing to the great variety of rocks included under them. 

 The same author gives the name lusitanite to a mesocratic form 

 of riebeckite-syenite found at Alter Pedroso, Portugal. This 

 rock contains 50-60 per cent, of riebeckite, and is associated 

 with the normal leucocratic riebeckite-syenite. 



The useful research of Rastall and Wilcockson on the 

 accessory minerals of the Lake District was carried out by the 

 method of crushing large samples and panning the resulting 

 sands. The results showed, as might have been expected, that 

 thin sections are entirely inadequate to give an idea as to the 

 amount, or even kind, of the accessory minerals present in the 

 rocks. An unexpected feature was the universal occurrence 

 of pyrrhotite and the rarity of magnetite as the prevalent ore- 

 mineral. This work has an obvious bearing on the question 

 of the origin of the heavy minerals in sedimentary rocks. 



Mennell has described contact-metamorphism by the Dart- 

 moor granite, which has converted the adjacent Carboniferous 

 sediments into interesting cordierite- and andalusite-bearing 

 rocks. 



Foye concludes that the so-called granite batholiths of 

 Ontario were formed by concordant injection into a fissile lime- 

 stone terrane, which is consonant with the remarkable banding 

 of most of the rocks in this district. He suggests the term 

 stromatolithic as a better description of the structure and 

 mode of intrusion. 



In his classification paper Holmes proposes a five-fold 

 division of igneous rocks established upon the " saturation " 

 criteria of Shand. Each of the groups is then divided according 

 to the ratio of albite to orthoclase, and of albite to anorthite. 

 It is not made clear whether all the albite in the rock is to be 

 used in each of these ratios. The ratio of felsic to mafic 

 minerals, shown to be very important in recent differentiation 

 work, is not utilised as a factor in classification until the fore- 

 going are exhausted. The paper is of great value in drawing 

 attention to classification on a quantitative mineralogical basis. 

 3 



