The commoner mineral springs of the formation, as might be anticipated, from the very general diffusion of the oxide to which it owes its color, are chalybeate. There are districts in Easter-Ross and the Black Isle in which the traveller scarcely sees a runnel by the way-side that is not half choked up by its fox-colored coagulum of oxide. Two of the most strongly impregnated chalybeates with which I am acquainted gush out of a sandstone bed, a few yards apart, among the woods of Tarbat House, on the northern shore of the Frith of Cromarty. They splash among the pebbles with a half-gurgling, half-tinkling sound, in a solitary but not unpleasing recess, darkened by alders and willows; and their waters, after uniting in the same runnel, form a little, melancholy looking _lochan_, matted over with weeds, and edged with flags and rushes, and which swarms in early summer with the young of the frog in its tadpole state, and in the after months with the black water-beetle and the newt. The circumstance is a somewhat curious one, as the presence of iron as an oxide has been held so unfavorable to both animal and vegetable life, that the supposed poverty of the Old Red Sandstone in fossil remains has been attributed to its almost universal diffusion at the period the deposition was taking place. Were the system as poor as has been alleged, however, it might be questioned, on the strength of a fact such as this, whether the iron militated so much against the living existences of the formation, as against the preservation of their remains when dead.