294 ON THE IGNEOUS METAMORPHOSIS [Ch. XIV. 



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 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 sedimentary deposits disputed. The arrangement of 

 primary slates incompatible with their being altered deposits. These slates 

 contain elements not found in sedimentary rocks. The transfusion of 

 alkalis analogous to that of magnesia in dolomite. Objections to such 

 transfusions. The primary slates of Dartmoor and 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. 



THE metamorphosis of stratified deposits by the contact of 

 igneous rocks in a state of fusion or incandescence, appears to 

 be established by such a legitimate train of deductions, that 

 it will probably be esteemed an act of great presumption to 

 dispute its accuracy. And any objections advanced against 

 this hypothesis, may naturally meet with a less candid consid- 

 eration than the topics already discussed; because it is the 

 offspring of the Plutonic theory, which has grown with its 

 growth, and which certainly is so plausible, and so well 

 adapted to give strength and support to its parent, and is 

 withal so fascinating, that even its adversaries must attack it 

 with no little reluctance. 



In a former chapter it was attempted to prove, that the 

 evidence by which the analogy between the primary and 



