THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE V. VOL. VIII. 



No. V. — MAY, 1911. 



With deep regret we record the death of our old and valued friend 

 Professor Thomas Rupert Jones, F.R.S., F.G.S., 



Editor-in-chief of this Magazine for the first twelve months of its 

 career, 1864-5, Avho passed away peacefully, after a long and 

 useful life, at " Penbryn ", Chesham Bois, Bucks, April 13, 1911, 

 aged 91 years. 



He was the author and editor of numerous hooks and memoirs. 

 From 1850 to 1862, Assistant Secretary to the Geological Society of 

 London, and Editor of the Quarterly Journal. 



In 1858 he was appointed Lecturer on Geology at the Royal 

 Military College, Sandhurst, and a resident Professor in 1862 ; 

 subsequently he served on the Staff College until his retirement 

 in 1880. l 



OJRTG-TTST j^IL, AETIOLES. 



I. — Calcite as a Primary Constituent oe Igneous Rocks. 



By Rachel Woreman. 



PLATES XI AND XII. 



DURING one of the excursions arranged by the International 

 Geological Congress held in Sweden, 1910, we visited, under 

 the leadership of Professor Hogbom, a group of islands skirting the 

 shore north of Sundsvall, on the Gulf of Bothnia. Among these 

 islands Alno and Langorsholmen are of particular interest on account 

 of a complex of alkali igneous rocks forming the whole of the latter 

 and the northern corner of the former. It is to this small but highly 

 interesting group of rocks that I wish to call the attention of the 

 reader, since apart from the short but convincing ' guide ' prepared by 

 Professor Hogbom (1), scarcely anything has been written on the 

 subject in the English language. The expedition was very skilfully 

 planned, and we were thus enabled to visit several critical exposures 

 and collect numerous specimens for microscopic study. 



As one approaches the two islands mentioned above, a marked 

 change in scenery presents itself. The coast of Sweden is protected, 



1 For Ms life and works see Geol. Mag., 1893, pp. 1-3 (with a portrait) ; 



and op. cit., November, 1909 (Birthday portrait and notice), p. 481. Elected 

 F.G.S. 1852 and F.K.S. in 1872. 



decade v. — vol. vni. — no. v. 13 



