464 ME. H. H. HEAD ON THE [vol. lxxix, 



Table III. — Analyses of Aenage Contaminated Rocks. 



VI. VII. 



VIII. 



Si0 2 



62-39 



0-99 



17-33 



0-48 



47-88 

 1-49 



26-35 

 0-95 



69-84 

 0-60 



13-16 

 1-45 



2-27 



TiO, 



A1.-.0-J . 



Fe.C0 3 



Cro0 3 



nt. fd. 



nt. fd. 



v 2 o 3 



FeO 



nt.fd. 

 7-19 

 0-18 



nt. fd. 



nt. fd. 

 12-01 



MnO 



(CoNi)O 



0-18 0-15 

 nt.fd. nt.fd. 



o-oi o-ii 



291 2-13 

 2-87 1 -Ofi 



BaO 



0-03 

 2-10 

 2-81 

 0-48 

 3-41 



CaO 



MgO 



KoO 



1-31 



5-68 

 3-07 

 nt.fd. 

 0-09 

 0-06 

 0-14 



o-oi 



009 



NaoO 



Li»0 





H 2 0at 105° C 



H.,0 above 105° C. ... 

 p. 2 o 5 



Oil 



1-47 

 0-22 



023 

 1-32 

 0-32 



FeS* 



Fe 7 S 8 



0-05 



0-58 



023 

 0-16 



CO- 



0-42 0-23 



Totals 



100-24 



100-20 



100-01 













VI. Contaminated Rock of Arnage Type, quarry at the roadside, half a mile north- 

 east of Mains of Drumwhindle, Arnage. Anal. E. G. Radley. 

 VII. Contaminated Rock of Arnage Type, Carding Hill, 700 yards south-south-east 



of Arnage House, Arnage. Anal. E. G. Radley. 

 VIII. Contaminated Rock of Ardlethen Type, quarry at the roadside, 340 yards 

 south-south-east of Ardlethen. Anal. E. G. Radley. (See p. 467.) 



in intimate association, but it may be said that the main type is 

 a quartz-cordierite-f elspar-biotite-rock (see fig. 4. p. 462). 



The average diameter of the grains in these rocks is 1 to 2 mm. 

 Usually there is a well-expressed fluxional structure, shown by the 

 orientation of the biotite-flakes and the longer axes of cordierite 

 and felspar-crystals. But rarely in this type is undulose extinction 

 in the quartz observed, and the fluxion appears to be the result of 

 flow of a pasty crystal-mush. A broader banding is often seen by 

 the alignment of streaks of varying composition, and this is 

 emphasized also by the filming-out of xenolithic relics. On a 

 smaller scale is a patchiness observed in slice, evinced in cordierite- 

 rich or biotite-rich streaks or patches of small size. Akin to these 

 banded and patchy rocks are some which show imperfect kneading 

 of the sediment-magma mixture. These rocks are of the usual type 

 of cordierite-biotite-quartz-plagioclase-rock, but have certain bands 

 rich in cordierite, often crowded with small spinels and biotite- 

 plates ; these bands appear to represent material largely of 

 sedimentary origin, which has been but imperfectly incorporated 

 in the contaminated magma. These streaks blend imperceptibly 

 with the matrix, and appear to represent a very advanced stage of 

 incorporation of xenoliths. 



Certain of the bands in the Arnage Type are almost of granitic 

 nature, being pale in colour and poor in cordierite. 



