No. 5.] HUNT — PRE-CAMBRIAN ROCKS. 273 



On these rocks in Charnwood Forest, in the same Journal, Hill <k 

 Bonney, Nov. 1887, p. 753, and May, 1878, p. 199. 



See farther. Hunt, Chemical and Geological Essays, pp. 34, 269, 

 270, 272, 278, 383; also his Azoic Rocks, part I (Second Geol. Survey 

 of Penn., 1878), pp. 187, 188. 



For the rocks of the Ardennes see Memoir sur les Roches dites 

 Plutoniques, etc. (4to, pp. 264), by de la Vallee Poussin and Renard, 

 from Memoires de I'Acad. Royale de la Belgique for 1876; Memoire 

 sur la Comp. Mineralogique du Coticule, by Renard, from the same 

 for 1877 ; and The Mineral ogical and Microscopical Characters of the 

 Belgian Whetstones, by Renard, Monthly Microscopical Journal for 

 1877, Vol. xvii. p. 269. Also Gosselet and Malaise, Terrain Silurian des 

 Ardennes, Bull. Acad. Roy. de la Belgique (2) No. 7, 1868 ; Dewalque, 

 Terrain Cambrien des Ardennes, Ann. Soc. Geol. de la Belgique, torn. 

 I, p. 63 ; and farther, Hunt, Chem. and Geol. Essays, p. 270.] 



Appendix. 



Since the above paper was read the author ha.s received (No- 

 vember, 1879) a private communication from Prof. L. W. Bailey, 

 giving his latest results as to the pre-Cambrian rocks of southern 

 New Brunswick, which confirm what has already been said 

 about that region. Bailey separates the Huronian into a lower 

 division, for which he reserves the name of Coldbrook, consisting 

 chiefly of petrosilex rocks, and an upper division, the typical 

 Huronian, called by him the Coastal group. Ho adds that there 

 is between the two a marked physical break, which is indicated 

 by a stratigraphical discordance, and by the presence in the 

 lower part of the Coastal group of coarse conglomerates made 

 up from the ruins of the Coldbrook or underlying division. This 

 corresponds to the break between the similar Arvonian and Hu- 

 ronian in South Wales. 



At the meeting of the British Association for the Advance- 

 ment of Science at Sheffield in August, 1879, Dr. Hicks read 

 a paper on the Classification of the British Pre-Cambrian 

 Rocks, which is published in the (jeological Magazine for Octo- 

 ber, 1879. He concludes that the Pebidian is '' a group of 

 enormous thickness, which is largely distributed over Great 

 Britain, where it has a prevailing strike of N.N.E. and S.S.W., 

 or from this to N.E. and S.W." In addition to the localities 

 which we have already mentioned in Great Britain, he notes its 

 occurrence in Shropshire and in Charnwood Forest, and also in 

 the northwest of Scotland, where, as elsewhere, it enters largely 

 into the Lower Cambrian conglomerates. The group is con- 

 VoL. IX. 8 No. 5. 



