8 Hi c Irish .'\attiralist. Janiiai-y, 



BELFAST NATURALISTS FIELD CLUB. 



XOVKMBKR 6. — GK0I,0G1CAL SKCTIOX. — KXCLRSION TO SOUIRE'S 



Ilii.r,.— The object of the excursion was to examine the Chalk quarries 

 on the side of Squire's Hill. There was a large attendance of members. 

 In the first two visited the chief features of interest were the fine exoo- 



A 



sures of hard white chalk, traversed b}* vertical d3'kes of basalt, the chalk 

 in their vicinity being much altered. lu the third quarry a good section 

 was exposed of Chloritic vSanus, passing upwards into Chloritic Chalk, 

 surmounted by hard white chalk. 



NovKMBKR 24.— Geological vSection.— Lecture by Mr. James 

 Slrachan on " Petrological T\-pes of Basalt in County Antrim.*' The 

 chief portion of the lecture was devoted to a suggested rational classi- 

 fication of the basaltic rocks of Co. Antrim, according to their varying 

 basicity. Three main classes were recognised and sub-divided as fol- 

 lows:— I. Basalts without Olivine (basaltic Andesites). A. Flow 

 type — Basalt of vSpanish Bay, Giant's Causeway. B. Intrusive type — 

 Dolerite of the neck at Carnmoney Hill, 11. Olivine Basalts. A. 

 Flow type— The common olivine basalt of the district, with olivine in- 

 creasing from occasional grains to plentiful porphyritic crystals. B. In- 

 trusive t\pe — The common olivine-dolerite of the district, with varying 

 amount of olivine — e.g. dolerite of the neck at Scawt Hill, and that of 

 Ballygalley Head. III. Basalts rich in Olivine. A. Flow type — 

 Containing excess of olivine in large phenocrysts, minimum of felspar 

 and augite, and colourless interstitial glass ; north side of Carnmoney 

 Hill. B. Intrusive type — Dolerite rich in olivine ; Slieve Mish. These 

 types of basaltic rocks were all illustrated by hand-specimens and 

 numerous microscopic sections. In conclusion, the lecturer referred to 

 several peculiar features of the local basalts, such as the fairly common 

 occurrence of " tube-amygdaloid'" at the basal portion of man}' of the 

 Co. Antrim flows, and the complete inclusion of primary minerals, such 

 as felspar and augite, in uatrolite and other zeolites. 



November 23 :— Geological Section.— Dr. A. R. Dwerrvhouse, 

 1\G.S., Lecturer in Geology in the Queen's University, delivered the first 

 of a series of lectures on practical petrology to members of the Belfast 

 Naturalists' Field Club. The lectures deal with the identification of 

 minerals by means of the microscope, and with the classification of rocks. 

 A noteworthy feature of the course is that each lecture is followed by a 

 demonstration class, in which the subj.^ct of the discourse is treated in a 

 practical manner, so as to give each member an opportunity of gaining 

 experience in the methods employed. By kind permission of the Vice- 

 Chancellor (the Rev. Dr. Hamilton) the lectures are being given in the 

 geological department of the l^niversity. 



