﻿506 PROF. S. H. EEYXOLDS OX THE [Xov. I908, 



abandant, but ilmenite is not present. Plentiful apatite-needles 

 penetrate all the other constituents. The most interesting fact about 

 the rock is, however, the occurrence of analcime, the presence 

 of vvhieh was first recognized by Mr. Harker. This mineral has 

 already been described in British dolerites from the followino- 

 localities : — Titterstone Clee ^; Car Craig - and Gullane Hill ^ in the 

 Edinburgh district; Spalefield"* near Anstruther; Bathgate^ in 

 Linlithgowshire, and Kidlaw in Haddingtonshire ; Dippin ^ (Arran) ; 

 and Hendre Quarry, Berwyns.' 



In the Bartestree rocks the analcime is usually fresh, but some- 

 times converted into some other zeolite in bundles of fibres. It 

 forms patches, frequently with a length of about half a millimetre ; 

 while in the Gullane-Hill rock they measure as much as 3 mm. in 

 diameter, and are not very much smaller in the rock from Claugh- 

 land Point (Arran). These patches fill up the gaps between the 

 felspar-laths, and their relations to the other constituents closelv 

 resemble those in the Dippin rock figured by Mr. Harker,^ and that 

 from Spalefield described by Dr. Flett. 



There is nothing in the Bartestree dolerite to suggest the former 

 presence of nepheline, and the general freshness of the felspars 

 and the absence of varieties rich in soda make it improbable that 

 the analcime is due to the alteration of felspar, as is suco-ested 

 by Mr. Young in the case of the Gullane-Hill rock. It seems 

 probable, then, that the analcime is of primary origin, as is main- 

 tained by Mr. Harker with regard to the Dippin rock. Owino- 

 to the presence of analcime, this rock may be grouped with the 

 teschenites. 



Sections showed the occurrence of doleritic rocks at a number of 

 points (see diagram, p. oO-i) farther towards the centre and the 

 northern margin of the dyke. Thus rocks from the spots 43, 51 

 & 52 are of the same general type as that just described, the 

 serpeutinized olivine being extremely abundant. Analcime is 

 especially plentiful at 51 (PI. LII, fig. 1) and 52. A rock from the 

 spot numbered 56, still farther towards the centre of the dvke and 

 an identical rock from 60, near the northern margin, are also weU- 

 marked dolerites but of a rather diff'erent type : the serpeutinized 

 olivine, which shows good crystal-outlines, is not so abundant as in 

 the rocks just described, and analcime does not occur. Augite, both 



'^ S. Allport, Quart. Journ. Geol. Soc. vol. xxx (1874) p. 550. 



2 J. J. H. Teali, ' British Petrography ' 1888, p. 191 & pi. xxii, fig. 1. 



' J. Young, Trans. Edin. Geol. Soc. vol. viii (1903-1905) pp. 3'26-35* 



* J. S. Flett, Mem. Greol. Surv. Scot. Appendix to ' The Geolo^^v of Eastern 

 Fife '1902, pp. 392-93. "-^ 



^ ' Summary of Progress of the Geological Survey for 1905 ' 1906, pp. 74 & 75. 



^ A. Harker, in Mem. Geol. Surv. Scot. ' Geology of Xorthern Arran* 

 &c.' 1903, pp. 112-14. 



■^ T. H. Cope & J. Lomas, Eep. Brit. Assoc. (Southport) 1903, pp. 664-65. 



1 am greatly indebted to Dr. Flett for drawing my attention to some of 

 the foregoing references. 



« 'Petrology for Students' 4th ed. (1908) p. 147. 



