BY W. N. BEN"SOX, W. S. DUN^ AND -W. R. BROWXE. 423 



will involve a close comparative study of the tectonic conditions attending the 

 vulcanicit y . 



The present study has shown that Benson's suggested correlation of certain 

 rhyolite flows in the Eocky Creek Series (48, p. 508) with the Pokolhin rhyolites 

 can be considerably extended. In the present incomplete state of our knowledge 

 of the Carboniferous rocks of New South Wales any hasty attempt at detailed 

 correlation is inadvisable, but there is every reason to hope that ultimately this 

 gi'eat series of rocks, so widespread in occurrence and so uniform in character- 

 istics, will be of the greatest stratigi'aphical importance. 



BIBLIOGRAPHY. 



4. D.wiD, T. W. E. and Sussmilch, C. A. — Sequence, Glaciation. and Corre- 

 lation of the Carboniferous Rocks of the Hunter River District, 

 N.S.W. Journ. Proc. Roy. See. N.S.W., liii., 1919 (1920), pp. 246- 

 338. 

 24. AxDERSox, E. M. and Radlet, E. G.— The Pitchstones of Mull and their 

 Genesis. Quart. Journ. Geol. Soc, Ixxi., 1915, pp. 205-217. 



47. Flett, J. S., and others. — The Geology of Newton Abbot. Memoir Geol. 



Surv. England and Wales, 1913, p. 57. 



48. Bexsox, W. N. — The Geology and Petrology of the Great Serpentine Belt of 



New South Wales. Part i. These Proceedings, xxxviii.. 1913, pp. 

 490-517. 



49. Bailev, E. B. — The Geology of the Glasgow District. Mem. Geol. Surv. 



of Scotland, 1911, p. 127 (Citing Neithammer) . 



50. and Grabhaii, G. W. — The Albitization of Basic Plagioclase Fel- 

 spar. Geol. Mag., 1909, p. 252. 



51. Flett, .1. S. and Dewet, H. — British Pillow-lavas. Geol. Mag., 1911, p. 



204. 



52. Browne^ W. R., and Walkom, A. B. — The Geology of the Eruptive and 



Associated Rocks of Pokolhin, N.S.W. .Journ. Proc. Roy. Soc. 

 N.S.W., xlv., 1911. 



53. Elsdex, J. v.— The St. David's Head Rock Series. Quart. -Journ. Geol. 



Soc, Ixiv., 1908, p. 289. 

 54fl. Bailey, E. B.— Geology of Ea.st Lothian, in Mem. Geol. Surv. Scot., 1910, 



p. 114. 



54b.- Geology of Glasgow District. Ihhl. 1911, p. 132. 



55. Tyrrell, G. W. — The Picrite-Teschenite Sill of Lugar. Quart. .Tourn. 



Geol. Soc, Ixxii., 1916, p. 100. 



EXPLANATION' OF PLATE XXV. 



Fig. 1. Soda rhvolite tuft" (1535): X 16*. Ordinary light. 



Fig. 2. Trachytoid quartz keratophyre (1448): X 16J. Ordinary light. At the 



top is a quartz-filled cavity with felspar prisms projecting into it. The 



light-coloured patch underneath is quartz poikilitically enclosing felspar. 

 Fig. 3. Hornblende lamprophyre (1450) : x 16i. Ordinary light. Showing irregular 



patches of zeolite. 

 Fig. 4. Trachytoid quartz keratophyre with orthophyric fabric (1499) : X 23*. 



Crossed nicols. 

 Fig. 5. Pilotaxitic pyroxene andesite (1439) : X 16i. Crossed nicols. 

 Fig. 6. Vitrophyric pyroxene andesite (1351) : X 15. Ordinary light. 

 Fig. 7. Andesine basalt (1497): X 15. Ordinary light. 

 Fig. 8. Albite dolerite (1451): X 15. Ordinary hght. 

 Fig. 9. Basalt of Werrie Series (1510); X 15. Ordinary hght. 



