6 EEPORT — 1880. 



occupied by rocks of true palasozoic age, whicli in many parts have passed 

 into a crystalline state.' 



I know of no case in Britain where the Carboniferous strata have 

 been thoroughly metamorphosed, excepting that in South Wales, beds 

 of coal, in the west of Caermarthenshire and in South Pembrokeshire, 

 gradually pass from so-called bituminous coal into anthracite. The same 

 is the case in the United States, in both instances the Carboniferous strata 

 being exceedingly disturbed and contorted. In the Alps, however, Sir 

 Roderick Murchison seems to have believed that Carboniferous rocks may 

 have been metamorphosed : a circumstance since undoubtedly proved by 

 the occurrence of a coal-measure calamite, well preserved, but otherwise 

 partaking of the thoroughly crystalline character of the gneiss in which 

 it is imbedded, and which was shown to me by the late Prof. Gastaldi, at 

 Turin, 



I am well acquainted with all the Permian strata of the British Islands 

 and of various parts of continental Europe, and nowhere, that I have 

 seen, have they suffered from metamorphic action, and strata of this age 

 are, I believe, as yet unknown in the Alps. This closes the list of 

 metamorphism of pateozoic strata. 



I will not attempt (they are so numerous) to mention all the regions 

 of the world in which Mesozoic or Secondary formations have undergone 

 metamorphic action. In Britain and the non-mountainous parts of 

 France, they are generally quite unaltered, but in the Alps it is different. 

 There, as everyone knows who is familiar with that region, the crystalline 

 rocks in the middle of the chain have the same general strike as the 

 various flanking stratified formations. As expressed by Murchison, ' as 

 we follow the chain from N.E. to S.W. we pass from the clearest types of 

 sedimentary rocks, and, at length, in the Savoy Alps, are immersed in 

 the highly altered mountains of Secondary limestone,' while 'the meta- 

 morphism of the rocks is greatest as we approach the centre of the chain,' 

 and, indeed, any one familiar with the Alps of Switzerland and Savoy 

 knows that a process of metamorphism has been undergone hj all the 

 Jurassic roclcs (Lias and Oolites) of the great mountain chain. Whether 

 or not any strata of Neocomian and Cretaceous age have been well meta- 

 morphosed in this region I am unable to say ; but it seems to be certain 

 that the Eocene or Lower Tertiary Alpine formation, known as the Flysch, 

 contains beds of black schists which pass into Lydian stone, and also that 

 in the Grisons it has been converted into gneiss and mica-schist, a fact 

 mentioned by Studer and Murchison. I also have seen in the country 

 north of the Oldenhorn, nummulitic rocks so far foliated that they formed 

 an imperfect gneiss. 



In Tierra del Fuego, as described by Darwin, clay slates of early cre- 

 taceous date pass into gneiss and mica-slate with garnets, and in Chonos 

 Islands, and all along the great Cordillera of the Andes of Chili, rocks of 

 Cretaceous or Cretaceo-oolitic age have been metamorphosed into foliated 

 mica-slate and gneiss, accompanied by the presence of granite, syenite, and 

 greenstone. 



