Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/459

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various parts of Scotland.

other respects preserving a perfect graywacke character, and being composed of distinctly rounded as well as crystallized grains of quartz, joined by a common cement.

It is plain that there will be a point of gradation where it will be impossible to say to which of the two the rock in question ought to be referred, although the extremes are perfectly characterized, in the one case by the laminar form of the quartz and mica, in the other by its granular disposition. I shall not be surprised if future observers discover that the rocks of the graywacke structure alternate here with those of the micaceous schist. Should this be the case, it will confirm the supposition which I have suggested in other parts of these papers, that no real and well defined line of distinction exists between the transition and primitive rocks, but that they form a graduating series of one single formation; a series so gradual as to render it expedient once more to return to the most simple division of rocks, into primary and secondary.

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