Geology and Mineralogy. 393 



the extent, effects and geological history of faultings and denu- 

 dation, particularly in the Scottish Mountain region. 



With regard to the Highland controversy he points out that 

 Macculloch, nearly seventy years ago, took the first right steps in 

 the investigation of the region, proving the existence of a great 

 formation of red sandstones and quartzyte, distinct from the " Old 

 Red," and finding some fossils in the quartzytes that have since 

 heen proved to be Paleozoic ; and recognizing its unconformabil- 

 ity to underlying crystalline rocks and its being overlaid with 

 apparent confbrmability by other crystalline schists and gneisses. 

 In 1854, Mr. Charles Peach discovered other fossils in the 'forma- 

 tion which settled the question as to Paleozoic age. In 1856, 

 Prof. Nicol showed that Macculloch's " Primary Red Sandstone " 

 formation, included two series, an upper fossiliferous, and a lower 

 unfossiliferous which was unconformable to the rest ; and to the 

 latter he gave the name of the Torrid on sandstone. In 1859 he 

 reached, in opposition to other investigators, the conclusions 

 which are now admitted facts, even to the latest — that the appar- 

 ently conformable succession of this early Paleozoic series into 

 overlying schist and gneiss, was " due to the thrusting of the 

 crystalline rocks over the sedimentary by great overthrow faults " 

 comparable with those found in the Alps. These results were 

 published by Professor Nicol in the Quarterly Journal of the 

 Geological Society for 1861. The conclusion was afterward sup- 

 ported by some other observers, but it took more than twenty-five 

 years for his results to gain general acceptance. 



The review of the close relations between Scottish and Scandi- 

 navian geology as regards geography, strata, mountains and 

 mountain-making, faulting and denudation, is of special interest. 

 The Scottish Highlands, with the Hebrides and Donegal, Orkney 

 and Shetland, are, Prof. Judd observes, " mere outliers of the 

 Scandinavian peninsula ;" and geographical separation took place 

 as late as the Glacial era. 



He recognizes fully the light with regard to the mountain 

 formations which the Highlands received from the work of Prof. 

 Rogers on the Appalachians. But he does not see fit to give 

 credit for the principle that, among crystalline rocks, lithology 

 may serve as a substitute for paleontological evidence ; and he 

 even throws discredit on the term "fundamental gneiss" of 

 Murchison. His views on this point we fully endorse ; and one 

 sentence is almost in the words of an article by the writer read in 

 August last before the geological section of the American Asso- 

 ciation. We cite a paragraph : 



" I confess that, speaking for myself, I am not sanguine as to 

 the success of such endeavors. The miserable failures which we 

 have seen to have attended similar attempts, in the case even of 

 far less altered rocks, where identifications have been based on 

 mineralogical resemblances only (and in connection with which 

 definite paleontological or stratigraphical evidence has been sub- 



Am. Jour. Sci.— Third Series, Vol. XXX, No. 179.— Nov., 1885. 

 25 



