“Quid magis est saxo durum ? quid mollius unda ?

Dura tamen molli saxa cavantur aqua.”

The condition of Central Scotland during the long period represented by the Secondary formations is involved in darkness. On the east and west coasts of Scotland rocks of Secondary age occur north of the Grampians, but of the physical history of Central Scotland during the time these rocks were deposited, we know nothing. From the time of the deposition of our Upper Coal-beds, or, it may be, of some Permian Sandstones, up till the time when the whole island was locked fast in one immense mantle of ice, we are almost entirely ignorant of what was going on in that part of the country which lies between the Grampians and the Forth. And the man who shall decipher for us the physical geography of that period, and reveal to us the old surface of that district, with its vegetation and animal productions, prior to the time of the Boulder Clay, will have rendered no small service to the cause of Scottish geology.

But although we have not as yet been able to trace the old surface of the land, we are not altogether without data to guide us in our researches. One thing is clear and certain,—a great change was taking place over the whole face of this region.