SCIENCE- GOSSIP. 



C. nastes . 

 rossii 

 werdandi 

 coeandiea 



may a. . 



ta/merlcma 



Dusky greenish. 

 Yellow. 



Greenish-white. 

 Dusky greenish. 

 Greenish-yellow to green- 

 ish-white. 

 Very dusky olive-green. 



All the orange species are liable to a dimorphic 

 whitish coloration in $ . 



In Group ]., /J., ('. pahiciio and C. anthyale are 

 somewhat abnormal, insomuch that the females 

 have but a faint trace of spots on the marginal 

 band, and that only occasionally. 



In Group II., C. 'christopki and C. erschoffi are 

 remarkable, the former for the brownish colouring 

 of the wings, the latter for its golden-yellow colour ; 

 it, however, approaches C. saga/rtia in general 

 appearance. 



(To hi- conl iimed?) 



(jEOLOOY in antkim. 



By E. Reginald Sawer. 



TDECENT 



field-work in Antrim has raised 

 some doubt in my mind as to whether the 

 commonly accepted explanation of the nature of 

 the metamorphosis by which the Chalk of the dis- 

 trict has become indurated and crystalline can be 

 accepted as altogether satisfactory. The fine series 

 of sections along the scarps of Antrim show the 

 following Mesozoic rocks in order : — Trias, Lower 

 Lias, Upper Cretaceous. If we take, for the pur- 

 pose of illustration, the section exposed from 

 Garron Point to Cushendall, near the coast, the 

 eroded surface of the Chalk will be seen to be 



of weakness caused by a fault-plane. The chief 

 interest attaching to these dykes lies in the fact 

 that though of considerable dimensions — the latter 

 being fully sixty feet in diameter— the meta- 

 morphism induced in the stratified rocks as a result 

 of contact with these igneous masses can only be 

 traced, at the most, within a few inches of the 

 actual point of contact. Contact-metamorphism 

 is, in fact, always distinguished by its extremely 

 local character, and as a rule the extent of meta- 

 morphism, and the distance to which it can be 

 traced, bear a marked relation to the volume of the 



Cushendall 



Garron Point 



I. Upper and Lower Basalt : Ik. Pisolitic Iron-ore ; II. Indurated Chalk ; III. Lias and Rbaetie 



IV. Trias; V. Lower Old Red Sandstone (Dingle) ; VI. Metamorphic Bocks (? Archaean); 



.c, Basalt Dyke ; 11, Felstone-porpbyry (Orthoclase-porphyry). 



overlain by two sheets of basaltic lava, separated 

 by a band of red pisolitic iron-ore ; while a layer 

 of reddish flint-gravel frequently intervenes 

 between basalt and Chalk, representing the 

 product of subaerial decay previous to the eruptive 

 epoch. The Chalk lying beneath the basalt is 

 altered and indurated, and it has very generally 

 been taken for granted that such marmorosis is a 

 result of contact with the lava. It seems, however, 

 to be a question whether this conclusion can be 

 fairly drawn when all the facts bearing on marmo- 

 rosis are duly taken into account. 



Further to the west the section shows the 

 Triassic beds penetrated by two important dykes 

 — the first, lying to the east, consisting of basalt ; 

 while the second, on which Cushendall is situated, 

 is composed of Orthoclase-porphyry (Felstone- 

 porphyrv), and has been erupted through the line 



igneous mass. In this particular case, however, 

 it is the lower bed of basalt alone with which we 

 have to deal, as the band of pisolitic ore affords 

 clear evidence of the subsequent eruption of the 

 upper bed. 



Such being the case, it would seem difficult to 

 account for the apparently uniform alteration 

 which has taken place throughout the relatively 

 immense thickness of the Chalk, by mere proximity 

 to the basalt. 



In the Crimea, sonic fifteen mile.- from Tchatyr 

 Dagh, indurated Chalk occurs similar to that of 

 Antrim, but without relation to any igneous intru- 

 sion. Again, in the Caucasus the chalk i< covered 

 by immense sheets of Andesitic lavas, bul retains 

 its norma] friable character. These two cases 

 sufficiently prove thai contact-metamorphism is 

 no1 essential to the induration of Chalk. 



H 3 



