CONTENTS. 



CHAPTER XIV. 



ARE THE PRIMARY SCHISTOSE ROCKS SEDIMENTARY DEPOSITS 

 ALTERED BY THE CONTACT OF IGNEOUS ROCKS ? 



Passage of primary slates into secondary rocks. Transitions of two kinds 

 mineral and mechanical the latter no criterion of identity. The 

 relative position of strata not easily determined the lias group of the 

 Botzberg. The capability of caloric to alter rocks. Lyell's remarks 

 on this subject. Sir James Hall's experiments on the fusion of rocks. 



The state of rocks next actual lavas also next trap-rocks in Skye 

 in Anglesea in Ireland. Dolomization. Strata next igneous rocks 

 only partially altered. These changes similar to the effects of caloric. 



Condition of primary strata next granite indicates a transmutation 

 of one earth into another. The contact of ignited granite and sediment- 

 ary deposits disputed. The arrangement of primary slates in compatible 

 with their being altered deposits. -These slates contain elements not 

 found in sedimentary rocks. The transfusion of alkalies analogous to 

 that of magnesia in dolomite. Objections to such transfusions. The 

 primary slates of Dartmoor and of the Hartz said to be altered 

 greywacke. Those of the Alps, altered oolitic strata. The association 

 of gneiss and limestone in Jungfrau of granite and limestone in Glen 

 Tilt and the Pyrenees. Conclusion Page 294? 



CHAPTER XV. 



DO THE PRIMARY ROCKS AFFORD PHYSICAL EVIDENCE THAT 

 THEY HAVE EXPERIENCED FISSURES, DISLOCATIONS, AND 

 OTHER MECHANICAL MOVEMENTS ? 



The apparent indications of displacements. The curvatures of rocks. 

 Alternations of curved and straight strata. Veins often tortuous in 

 straight beds. The colouring ingredients of rocks arranged in undula- 

 ting and contorted lines. Similar appearances in agates and alabasters 

 -also in igneous rocks. Sir James Hall's explanation of curved strata. 

 The moving power imaginary. The spheroidal structure of rocks. 

 Primary conglomerates not fragmentary. The secondary sometimes 

 mechanical sometimes concretional. Igneous and aqueous rocks also 

 conglomerated. Granite-veins their structure and composition in- 

 compatible with theory analogous to slate-veins and to certain 

 arrangements in crystalline rocks. Mineral veins different kinds of 

 veins of segregation in Cornwall. Definition of true veins objected 

 to. Intersection of veins no criterion of their relative ages. Re- 

 marks on the heaves and other supposed movements of veins. 

 Conclusion - 4 -"?'? ".-, : - 333 



