Vol. 50.] ANNIVERSARY ADDRESS OF THE PRESIDENT. 1 23 



case of the calcareous ashes of the Shap district, since, on the outer 

 edge of the metamorphic aureole, it is only the most finely-divided 

 calcite which has been decomposed. 



In addition to the above, the Lake District has yielded three 

 short papers which relate to the Skiddaw region. The first of these, 

 by Mr. Groom, is on a tachylyte associated with the gabbro of 

 Carrock Fell, and occurring in a vein about one inch thick. The 

 rock to which the Carrock Fell tachylyte most nearly approaches 

 appears to be the typical variolite of the Durance. It agrees with 

 this rock in the nature and behaviour of the varioles (spherulites), 

 in the character of the pyroxene-granules, and in the presence of 

 a green groundmass. The tachylyte is regarded as of Ordovician 

 age. 



Mr. Postlethwaite has contributed two papers, which relate to 

 eruptive rocks on the north-west side of Skiddaw. In Hause Gill, 

 which lies nearly due north of the summit of that mountain, are 

 two small exposures of a ' dioritic picrite' about 5 mile apart, 

 though probably forming one mass. This rock is described as being 

 of a dark olive-green colour, and consisting of several varieties of 

 hornblende with some felspar, serpentine, calcite, and other mine- 

 rals. The Author remarks that it is still more remote from a 

 typical picrite than the Little Knott rock, at no great distance, and 

 it may be regarded as one of the transitional forms between normal 

 picrite and normal diorite. He intimates that these eruptives may 

 all have been derived from the same magma, since the differences 

 are little more than have been shown to exist between different por- 

 tions of the exposure at Little Knott itself. The chief interest in 

 Mr. Postlethwaite's second paper centres in a comparison instituted 

 between a sheet of diabase, intrusive in the Skiddaw series near 

 Bassenthwaite, and a parallel bed of fine-grained grit. Half a 

 century ago a considerable quantity of antimony was obtained from 

 the locality. From the attendant circumstances he concludes that 

 the deposition of the metalliferous vein-stuff has been the result of 

 thermal action following the intrusion of the diabase. 



Wales. — With respect to the Principality, there have been papers 

 by Mr. Harker, Messrs. Cole and Jennings, and Prof. Lloyd Morgan, 

 dealing with subjects which have been more or less touched upon by 

 Sir Archibald Geikie in his first Presidential Address. On the 

 present occasion we have to consider two papers by Miss Raisin 

 and one by Messrs. Jennings and Williams. 



