﻿^XIV PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES. 



Fig. Pagb 



1 . Section of the hillside abo ve Tyddyn-dicwni 168 



2. Sections of the eastern and western trenches, Tyddyn-dicwni . 169 



3. Sketch-plan of the surface from which the iron-ore has been 



stripped (Tremadoc Iron-Mine) 171 



4. Section showing the mode of occurrence of the pisolitic iron- 



ore among the slate-rocks, in the iron-mine north of the 

 Penmorfa road, Tremadoc 172 



■5. Exposure in the Penmorfa flag-quarry 174 



1. Topographical map of ISTyasaland 191 



2. Geological map of Nyasaland 193 



3. The Karroo and the recent tuffs of the Nkana area [map] 202 



4. The Karroo and the lacustrine beds of the Mpata area [map] . 206 



5. The Karroo of the Mwapo & Sere River area [map] 208 



»6. The Karroo trough of the Western Nyika [map] 211 



7. The Karroo and the recent lacustrine deposits of the Mount 



Waller area [map] , 214 



8. The Karroo of the Lower Shire area [map] 216 



9. Sections through typical areas in Nyasaland 218 



1. Tuffs and banded cherts, exposed in a road-cutting south-west 



of Greenaun 257 



2. Plan of part of a stream half a mile south of Garranagerra ... 260 



3. Coarse volcanic breccia north-east of Glensaul School 261 



4-6. Sections from Garranagerra to Greenaun, from Glensaul to 

 the l'idge west of Greenaun, and from Tonaglanna to the 

 ridge east of Lettereeneen Hill 264 



1. Section of Brow Vein, Leadhills 290 



2. Section of Rampgill Vein, Nenthead 290 



3. Section of Foxdale Vein 291 



1. Diagrams illustrating the composition of fresh and altered 



country-rock 306 



2. Replacement of limestone by quartz and galena, Halkyn Mine 



(Flintshire) 310 



3. Metasomatic quartz, etc., Trecastell Mine (Conway) 311 



4. Rhyolitic breccia, showing replacement by galena 312 



