exhibits chiefly the productions of the land and its fresh waters; the other, as decidedly of marine origin, is charged with the remains of animals whose proper home was the sea. But the productions, though dissimilar, were in all probability contemporary, just as the crabs and periwinkles of the Frith of Forth are contemporary with the frogs and lymnea of Flanders moss. I had little time for exploration in the neighborhood of Elgin; but that little, through the kindness of my friend Mr. Duff, I was enabled to economize. We first visited together the outlier of the Weald at Linksfield. It may be found rising in the landscape, a short mile below the town, in the form of a green undulating hillock, half cut through by a limestone quarry; and the section thus furnished is of great beauty. The basis on which the hillock rests is formed of the well-marked calcareous band in the Upper Old Red, known as the Cornstone, which we find occurring here, as elsewhere, as a pale concretionary limestone of considerable richness, though in some patches largely mixed with a green argillaceous earth, and in others passing into a siliceous chert. Over the pale-colored base, the section of the hillock is ribbed like an onyx: for about forty feet, bands of gray, green, and blue clays alternate with bands of cream-colored, light-green, and dark-blue limestones; and over all there rests a band of the red boulder-clay, capped by a thin layer of vegetable mould. It is a curious circumstance, well fitted to impress on the geologist the necessity of cautious induction, that the boulder-clay not only _overlies_, but also _underlies_, this fresh-water deposit; a bed of unequivocally the same origin and character with that at the top lying intercalated, as if filling up two low flat vaults, between the upper surface of the Cornstone and the lower band of the Weald. It would, however, be as unsafe to infer that this intervening bed is older than the overlying ones, as to infer that the rubbish which chokes up the vaulted dungeon of an old castle is more ancient than the arch that stretches over it. However introduced into the cavity which it occupies,--whether by land-springs or otherwise,--we find it containing fragments of the green and pale limestones that lie above, just as the rubbish of the castle dungeon might be found to contain fragments of the castle itself. When the bed of red boulder-clay was intercalated, the rocks of the overlying Wealden were exactly the same sort of indurated substances that they are now, and were yielding to the operations of some denuding agent. The alternating clays and limestones of this outlier, each of which must have been in turn an upper layer at the bottom of some lake or estuary, are abundantly fossiliferous. In some the fresh-water character of the deposit is well marked: Cyprides are so exceedingly numerous in some of the bands, that they impart to the stone an Oolitic appearance; while