182 THE GEOLOGIST. 



hour nearly as it rose above the sea, save in the effects of denudation 

 and atmospheric weathering of long past ages, and in its thin crust of 

 grey lichens, and its mantle of scanty herbage, which thus may grow 

 where Coal and Tertiary plants during former eras found scanty 

 sustenance. 



In our own isles, all that remains of the first land are the old 

 gneissic regions in the Orkneys, and in the north of Scotland, near 

 Cape Wrath ; and these we have questioned hitherto in vain for any 

 traces of living things. All their secrets are still fi.rmly locked up in 

 their compact, crystalline, adamantine breasts. 



Whether any traces of the old gneissic rock — the equivalent of the 

 Laurentian Group — are yet to be found beneath the mountain-masses 

 of the primitive sediments formed upon its shores (our Cambrian 

 rocks, the equivalents of the American Huronian group), further 

 researches, or rather, perhaps, future excavations or borings, can alone 

 determine. Probably, however, the original lands, on the shores of 

 which the Welsh and Irish Cambrian deposits were formed, have sunk 

 beneath the ocean with that old great western continent, the debris of 

 which remains in the Upper Paleeozoic and Ti'iassic deposits. 



We must, then, for the present, lea.ve the nature and conditions of 

 the first land in that obscurity in which ages of time have enveloped 

 it, and turn to the earliest stratified deposits on its shore, — our 

 Cambrian or " bottom-rocks," — for our first intelligible data of the 

 earth's early history. 



Some portions of these primary sediments remain in Caernarvon. 

 The grits, 8,000 feet thick, of Harlech, in North Wales, belong to this 

 age ; and equivalent rocks rise from beneath the Lower Silurian near 

 St. David's Head, in South Wales. Vast masses are also found at 

 Bray Head, in Ireland, and a patch also probably occurs at Charnwood 

 Forest, in Leicestershire, although the last is possibly only an altered 

 Silurian deposit. 



For a long time it was believed, from their crystalline character, 

 that the schists, quartzose, and felspathic rocks of the Isle of Anglesea 

 were more ancient than any of the strata of the adjacent mainland. 

 But this is not the case, for it is now well ascertained that they are 

 but altered Silurian beds, and tliat the rocks from which they, as well 



