304

ON THE ANCIENT GRAUWACKE ROCKS

of Sir Roderick Murchison appeared,—one of those greatworks which form eras in the history of science, and fromwhich, as from the charts of some distinguished voyager, afterexplorers have learned to shape their course aright, and torecognise as familiar and easily definable, tracts previously un-named and unknown. In both the old world and the new,the great divisions first laid down in this work by Sir Rode­ rick have been detected and identified, and an introductorybook added to the organic history of our planet, from the richand varied materials which they supply. Eor, however, se-veral years after its publication, our Scottish Grauwacke con-tinued to remain a terra incognita, as before; for though thereappeared from time to time truthful descriptions of the de-posit itself, its place in the scale was still doubtful. Twoyears after (1841), Mr James Nicol,—now Professor of Geo-logy in Queen’s College, Cork,—produced his Prize Essay onthe Geology of Peeblesshire; and to an accurate descriptionof the mineralogical components of the Grauwacke of thatcounty added a new locality for its fossils, in Grierston, nearTraquair, where, in a slate quarry, there occur thin but con-tinuous layers of graptolites, often in a state of the most ex-quisite keeping. Some of the finest Scottish specimens ofthis ancient organism which I have yet seen I have derivedfrom this Grierston deposit. We also find Mr Nicol refer-ring, in his Essay, to that limestone quarry of Wrae Hill inwhich Sir James Hall had found his fossil shells; but itslime, when he wrote, had been exhausted, or so covered upby the rubbish of the workings, that its organisms could bedetected no longer. “ It strikes one as a melancholy reflec-tion,” we find him saying, “ when leaving this deserted quarry,where the wild whistle of the mountain sheep shows howseldom their solitude is invaded, that these relics of formercreations, which, if preserved to science, might have addedan interesting page to the world’s history, should have thus