﻿Yol. 66.] THE METALLOGENY OF THE BKITISE ISLES. 281 



10. The Metallogeny of the British Isles. By Alexander Mon- 

 ceieff Einlayson, M.Sc, F.G.8. (Read December loth,. 

 1909.) 



[Plate XXIII— Map.] 



Contents. 



Page 



I. Introduction 281 



II. Epochs of Sub-Crustal and Igneous Activity in the British Area ... 282 



III. Metallogenetic Epochs in the British Area 283 



IV. Classification of the British Ore-Deposits 292 



V. Conclusions , 292 



I. Inteolectiox. 



The recent development of the geographical method of studying 

 ore-deposits is due to Prof. L. de Launay, who first pointed out 

 its application in 1897. His later works on this plan include 

 examinations of the ore-deposits of Africa, Italy, and Siberia. 1 

 His object is to delineate the various regional types of ores, and 

 to show their intimate genetic relation with tectonics and with 

 petrographic provinces, the regional types being termed ' metallo- 

 genetic provinces \ The same method has been applied by Dr. 

 J. Malcolm Maclaren in his * auriferous provinces \~ We have 

 thus, in the science of ore-deposits, the application of methods 

 analogous to those exemplified in Suess's ' Antlitz der Erde,' — ■ 

 methods which aim at correlating detached observations, and bring- 

 ing our knowledge of the ore-deposits of an area into relation with 

 our knowledge of its geological structure. 



In the present paper an endeavour is made to work out the 

 distribution of ore-deposits in the British Isles, and to determine 

 the relationship of the ores to the tectonics of the country, and to 

 the distribution of igneous rocks therein. Prof, de Launay's nomen- 

 clature has been followed, and I wish here to express my thanks 

 to him for his kindness in corresponding with me on the subject. 



The modern analytical classifications of ore-deposits, while 

 nominally on a genetic basis, involve, as subdivisions, factors of 

 varying importance — genesis, form, mineralogy, and structure. The 

 essential and accidental features are liable to be confused, and the 

 latter unduly emphasized. Further, theie is a tendency to make 

 the deposits, which show every conceivable gradation from one to 

 another, fit into the subdivisions of the classification. Indeed, 



1 • Sur les Types Regionaux de Gites Metalliferes ' C. R. Acad. Sci. Paris, 

 yol. cxxx (1900) p. 743: "Les Richesses Minerales de l'Afrique ' Paris, 1903 

 (Abstract in Rev. Gen. des Sciences, vol. xiii, 1902, p. 107"») : ' La Metallogenie 

 de l'ltalie' X^me Congres Geol. Internat. (Mexico, 1906) vol. ii, p. 565; 

 and ' La Metallogenie de l'Asie Russe ' Ann. des Mines, ser. 10, vol. xv (1909) 

 pp. 220 & 303. 



2 ' Gold ' LondoD, 1908. pp. 43 et seqq. 



