272 GEOGNOSY OF THE APPALACHIANS. [XIII. 



thence into Vermont and New Hampshire, by the presence of 

 staurolite and some other associated minerals, which mark with 

 the same unerring certainty the geological relations of the rock 

 as the presence of Pentamerus oblongus, P. galeatus, Spirifer 

 Niagarensis, or S. macropleura, and their respectively asso- 

 ciated fossils, do the relations of the several rocks in which 

 these occur." * 



I am convinced that these crystalline schists of Germany, 

 Anglesea, and the Scotch Highlands will be found, like those 

 of Norway, to belong to a period anterior to the deposition of 

 the Cambrian sediments, and will correspond with the newer 

 gneissic series of our Appalachian region. There exists, in the 

 Highlands of Scotland, a great volume of fine-grained, thin-bed- 

 ded mica-schists with andalusite, staurolite, and cyanite, which 

 are met with in Argyleshire, Aberdeenshire, Banffshire, and the 

 Shetland Isles. Rocks regarded by Harkness as identical with 

 these of the Scottish Highlands also occur in Donegal and 

 Mayo in Ireland. Through the kindness of the Rev. Professor 

 Haughton of Trinity College, and Mr. Robert H. Scott, then 

 of Dublin, I received some years since a large collection of 

 the crystalline rocks of Donegal, which I am thus enabled to 

 compare with those of North America, and to assert the exist- 

 ence, in the northwest of Ireland, of our second and third 

 series of crystalline schists. The Green Mountain rocks are 

 there exactly represented by the dark-colored chromiferous 

 serpentines of Aghadoey, and the steatite, crystalline talc, and 

 actinolite of Crohy Head ; while the mica-schist of Loch Derg, 

 with white quartz, blue cyanite, staurolite, and garnet, all 

 united in the same fragment, cannot be distinguished from 

 specimens found at Cavendish, Vermont, and Wind ham, Maine. 

 The fine-grained andalusite-schists of Clooney Lough are ex- 

 actly like those from Mount Washington ; while the granitoid 

 mica-slates from several other localities in Donegal are not less 

 clearly of the type of the White Mountain series. Similar 

 micaceous schists, with andalusite (chiastolite), occur on Skid- 

 daw, in Cumberland, England, the relations of which have 

 * Paleontology of New York, Vol. III., Introduction, page 93. 



