TACONIC QUESTION IN GEOLOGY. 1S7 



— 185. His citations of Messrs. Rogers. — 186. Studies in Westchester County ; tlie rocks chiefly Laurentian. 

 — 187. Gneisses and mica-schists of Manhattan Island described. — 188. Dana's statements reviewed. — 189. 

 Rise and fall of the doctrine of metamorphism. — 190. The Scottish Highlands ; views of Murchison and 

 Giekie, of Nicol, and of Hunt.— 191. Later studies of Hicks, Callaway and Lapworth ; their conclusions. 

 — 192. Recent vi'ork of Giekie and his assistants; the views of Murchison discarded. — 193. Giekie's so- 

 called metamorphism criticised.— 194. Origin of crystalline rocks ; the crenitic hypothesis. 



Chapter IX. — Conchisiuns. — 195. Sources of knowledge. — 196. The Taconian characterized; its mineralogy. — 197. 

 Its distribution in Nortli America. — 198. Its relations to organic life. — 199. The Uitpcr Taconic or Cam- 

 brian; its relations to Ordovician and Silurian. — 200. Relations of all these to Taconian, and views as to 

 the age of the latter. — 201. Succession of crystalline rocks in time. — 202. Deposition .of the Taconian. — 203. 

 Rocks related to Taconian in Brazil, India, Russia; studies in Brazil. — 204. In Guiana, Venezuela and 

 Trinidad. — 205. Crosby on Taconian in Trinidad. — 206. In Cuba, Jamaica and San Domingo. — 207. 

 Lustrous schists of the Alps. — 208. Hercynian clay-slate group; Taconian rocks in Norway. — 209. 

 Studies of Barrels in Spain. — 210. Apparent wide spread of the Taconian series. 



Note. — The late observations of Ford giveu in § 155, and those of Giekie and his 

 assistants in § 192, 193, have been published since this second part of the present paper 

 was presented in May, 1884. 



