CONTENTS. vii 



but common to the whole mass. The general structure dependent on 

 the aggregation of individual concretions, The layers of granite pos- 

 sessed of determinate bearings like strata. Structure of the'primary 

 schists. The nature and disposition of strata. The curvatures and 

 convolutions in the beds of primary rocks. Their angular and sphe- 

 roidal structure, resembling breccia and conglomerates - Page 91 



CHAPTER VII. 



ON THE RELATIVE POSITION, AND ON THE NATURE OF THE 

 GRANITIC AND SCHISTOSE ROCKS AT THEIR JUNCTION. 



Position of the primary schists next granite. They extend far over this rock, 

 through the transverse valleys in Cornwall. The mica-slate of Ireland 

 similarly situated, capping the granitic mountain of Lugnaquilla. The 

 Cornish strata skirt the granite in an irregularly undulating curve. 

 The same arrangement obtains in the Isle of Arran, in the north of 

 Scotland, and in the Alps. Dip of the strata at the junction, in 

 Arran, in Cornwall, in Galloway, apparently irregular not so 

 dependent on the structure of the primary rocks illustrated by sections. 



The anticlinal axis of primary districts said to be simple in each 

 geographical range not so in the Ocrynian range, nor in the Pyrenees. 



Composition of granite and primary schists at their junction in Corn- 

 wa ll } near Cherbourg, in Ireland, in lona and Mull, in Glen 

 Tilt, and near St. Paul de Fenouillet in the Pyrenees - - 119 



CHAPTER VIII. 



ON THE VARIOUS MODES IN WHICH THE GRANITIC AND SCHIS- 

 TOSE ROCKS ARE ASSOCIATED TOGETHER. 



The occurrence of granitic rocks in the primary schists in the form of 

 beds or courses in irregular bunches or masses in Cornwall, 

 Scotland, Ireland, andNorway. Portions of these schists also con- 

 tained in granite in Cornwall, in various parts of Scotland, and in 

 France. The primary strata traversed by granite-veins in Cornwall, 

 and in Scotland. Summary of the various appearances presented by 

 these veins - 143 



CHAPTER IX. 



ON THE MINERAL AND METALLIFEROUS VEINS IN THE PRIMARY 



ROCKS. 



Our knowledge of veins very imperfect and too hypothetical. The 

 definition of veins not correct. The following details on this subject 

 entirely drawn from Cornwall. Description of veins as seen on the sea- 

 shore, in quarries and similar open situations of small or concretionary 

 veins of larger veins, not confined to individual rock-concretions, 

 but traversing one or more layers or strata. These commonly called 



