2 lO 



NATURE 



[October 17, 191 2 



to Miss Ellis (Cambridge), who recognised it as a 

 graptolite with Ordovician affinities. 



Dr. A. W. Gibb (Aberdeen) read a paper on an 

 actinolitc-bearing roclc allied to serpentine associated 

 with tlie basic intrusion of Belhelvie. Towards tlie 

 northern end of this mass, which consists of trocto- 

 lites, serpentines, and allied types, there is a rock 

 whicli shows a large number of dark-green rounded 

 spots, set in a fine felt of paler green colour, full of 

 glancing needles. Under the microscope the spots 

 are seen to represent olivine, partly unaltered, partly 

 serpentinised, as well as granulitised and drawn out. 

 The rest of the rock is largely made up of actinolite 

 in small crystal flakes, and green spinel and abundant 

 magnetite are present. The exposure has recently 

 been blasted awa}'. 



Dr. Wm. Mackie described the volcanic rocks round 

 the Ord Hill of Rhynie, Aberdeenshire. The group 

 embraces at least three lava flows, with associated 

 tuffs and interbedded and overlying sedimentary rocks. 

 Flow brecciation is frequent, and the tuffs are rhyolitic. 

 The sedimentary rocks of the group consist of hard 

 siliceous grits, which, under the microscope, show 

 volcanic fragments. The whole of the group is char- 

 acterised by fine, secondary quartz infiltration veins. 

 They overlie the basic rocks of the younger Grampian 

 granite series, but are probably considerably older 

 than the oldest Old Red beds of the adjoining area. 

 The lavas, being of an acid type, cannot be correlated 

 with the interbedded andesites of the Old Red Sand- 

 stone. 



Mr. G. W. Tyrrell (Glasgow) described the allcaline 

 igneous rocks of Ayrshire. Recent work of the Scot- 

 tish petrologists shows that one of the greatest 

 developments of rocks characterised by primary anal- 

 cite is contained in the midland vallev of Scotland, 

 one centre being in .\yrshire, the other in the area 

 surrounding the Firth of Forth. Geologically these 

 analcite rocks are Carboniferous in age, having a 

 time-range from Carboniferous Limestone to Earlv 

 Permian. They occur in the form of stratiform sills, 

 lenticular intrusive masses, volcanic plugs, and as a 

 series of lava flows. No masses of true plutonic 

 habit are known. 



Passing to Wales, a paper was read by Mr. Edward 

 (ireenly on the origin of some of the mica-schists of 

 .\nglesev. The mica-schists of southern and central 

 .'\nglesey are holocrystalline rocks with strong parallel 

 structure, and composed essentially of quartz, alkali- 

 felspars, and white mica. Dr. Teall regards them as 

 broken-down and partially reconstructed porphyritic 

 felsites. Twenty-five years ago Dr. Callaway recog- 

 nised their felsitic origin, which the present investiga- 

 tions confirm. These schists, therefore, may be loolvcd. 

 upon in general as derived from acid igneous rocks. 

 In some areas mica schists in continuity with them 

 are found in intimate relations to schists of sedi- 

 mentary origin, so that, probably, pyroclastic material 

 was present in tlie original igneous series. 



Dr. Robert Campbell (Edinburgh) gave a valuable 

 ristimd of his recent investigations on the Lower Old 

 Red beds of Kincardineshire, showing that a thick- 

 ness of 3000 ft. ought now to be transferred to the 

 Downtonian, the uppermost group of the Silurian 

 svstem. At the base of the series near Stonehaven 

 there is 200 ft. of breccias interbedded with fine red 

 mudstones made up mainly of fragments of the under- 

 Ivinc (?) Upper Cambrian rocks, and resting uncon- 

 formably on them. Near Cowie Harbour there occurs 

 a thirlc belt of grey and greenish mudstones which 

 yield Dictyocaris in abundance. Ceratiocaris, Archi- 

 desmus, Eurypterus, and other forms have been obtained 

 from the same horizon, and in another bed numerous 

 plates of a new Cvathaspis have been found. These 

 interesting fossil finds, which in other areas do not 

 NO. 2242, VOL. 90] 



occur in rocks younger than the Upper Silurian, and 

 the lithological characters recall the typical Down- 

 tonian of. the south of Scotland. These beds pass up- 

 wards into the micaceous sandstone and conglomerates 

 of Stonehaven Harbour, which may be considered as 

 the base of the Lower Old Red Sandstone. The fish 

 remains were examined by Dr. R. H. Traquair, who 

 reported that the small scutes were referable to the 

 category of Cephalaspidian scutes, that the species to 

 which they belong is pretty certain, but additional 

 material is required before proceeding further with 

 identification. He described several specimens of a 

 beautiful new Cyathaspis, which he dedicated to Dr. 

 Campbell. 



Mr. C. J. Gardiner gave an account of the Silurian 

 inlier of Usk. It is an oval area, eight miles by four, 

 crossed by an important east and west fault. The 

 southern half is composed of two anticlines separated 

 by a fault. The axes of these folds run north and 

 south, and dip southwards. The western anticline is 

 the larger of the two, and shows Wenlock Shales and 

 Limestone and Ludlow beds. The northern half of 

 the inlier is far less simple than the southern in its 

 structure, and is more concealed by drift. The Wen- 

 lock Limestone is not met with in this half. The 

 simplest explanation is that the Wenlock Shale is 

 faulted against the Ludlow beds on both sides. As 

 the A3'mestry Limestone is absent from the area, it is 

 impossible to separate the Ludlow beds into an upper 

 and lower division. The main boundary faults are 

 crossed at several spots by minor east and west faults 

 which cause small lateral displacements. 



There were three important contributions from 

 the pateobotanical side. Dr. Marie C. Stopes 

 gave an outline of a controversy in New 

 Brunswick between the palseobotanists and the 

 stratigraphers. In the " Fern Ledges " of St. 

 John there is a rich fossil flora, but no animal 

 remains. Sir W. Dawson described the plants as 

 Devonian. Recent attempts have been made to in- 

 clude the beds in the Silurian for stratigraphic 

 reasons. The autlior's work in the field indicated con- 

 siderable overthrust. The unique series had recently 

 been redetermined. Type specimens had been lent by 

 the Canadian museums and brought to London and 

 Paris for comparison, resulting in the identification 

 of a large proportion of well-known European types 

 in the " Fern Ledges " flora as Carboniferous and 

 mostly typical of the Westphalian division of the Coal 

 Measures. 



Dr. W. T. Gordon read a paper on the fossil flora 

 of the Pettycur Limestone in relation to botanical 

 evolution. The flora of the Pettycur Limestone 

 (Lower Carboniferous) has a double interest. These 

 forms constitute fragments of the oldest known flora, 

 as Lower Carboniferous plants do not differ markedly 

 from the LTpper Devonian forms. Although the 

 Devonian flora is distinct from that of the Permo- 

 Carboniferous epoch, yet the organisation does not 

 indicate that the plants were primitive. The result of 

 Dr. Gordon's investigations was that the flora repre- 

 sented in the Pdtycur Limestone appears, on the 

 whole, to contain more generalised and simpler types 

 than occur in the Coal Measures and later strata, 

 and these tvpes mav be arranged in order so as to 

 suggest certain possible lines of evolution. 



Mr. W. R. Don (Dundee) read a paper on the nature 

 of Parka decipiens. This fossil is the onlv common 

 and quite the most characteristic fossil of the Lower Old 

 Red Sandstone of the Kincardine-Forfar-Perth area. 

 A re-investigation, chieflv microscopical, has been 

 attempted with the aid of Schultz's solution (strong 

 nitric acid and nolnssium chlorate"!. Most previous 

 investigators had pronounced it to be vegetable, 

 though Mantell, Lvell, and others considered it as an 



