Geological Society. 1035 



way are thus only one quarter of the width o£ the lines 

 emitted by the flame and narrower than the iron are lines. 



They are, however, three times as wide as the narrowest 

 known line, the red line of cadmium, for which 



2e=-006 A. 



An interferometer study of the resonance radiation is much 

 to be desired, for the above method of deducing the width of 

 the lines is somewhat circuitous. 



Laboratory of M. Bout} r , 

 La Sorbonne, Paris. 



CX. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 

 [Continued from p. 540.] 



January 21st, 1911. — Dr. Aubrey Strahan, F.ll.S., President, 

 in the Chair. 



ir piIE following communications were read : — 



1. * Geologv of the Country round Huntly (Aberdeenshire). 

 By William Robert Watt, M.A., B.Sc, F.G.S. 



In this area two distinct series of rocks can be distinguished — a 

 foliated, and a non-foliated series. In the former occur rocks 

 originally sedimentary and others originally igneous. In the non- 

 foliated series, which is wholly of igneous origin, three main 

 intrusions occur : — (1) The earliest and most extensive is a norite 

 with, as modifications due to differentiation, olivine - gabbros, 

 troctolites and ' picrites.' 



(2) Into this is intruded the heterogeneous mass known as the 

 Central Intrusion, which consists of three main types with no 

 distinct boundaries : — 



(a) At the margin occurs a fine-grained norite with pronounced mineral 

 banding. Nearer the centre of the mass is met (b) a biotite-plagioclase rock ; 

 and the centre itself is composed of (c) a garnet-monzonite. 



(3) The third large intrusion is the Carvichen Granitite, com- 

 posed chiefly of quartz, microcline, and biotite. 



Each of these masses produces some contact-alteration in the 

 surrounding foliated or non-foliated rocks. Where the Central 

 Intrusion or the Carvichen Granitite is intruded into the earlier 

 norite, a norite containing cordierite is produced. The original 

 norite, by absorption of sediment, produces also along its margin 

 a cordierite-norite. Similar types have been described by Prof. 

 A. Lacroix and Mr. A. N. Wine hell. 



Both types of cordierite-norite tend to pass into a rock composed 

 essentially of plagioclase, biotite, and garnet ; and this change, with 

 the gradual destruction of the hypersthene, can be seen in various 

 stages. 



