The rock appears in the course of the Elliot, a few hundred yards above the pastoral village of Arbirlot. We find it uptilted on a mass of claystone amygdaloid, that has here raised its broad back to the surface amid the middle shales and sandstones of the system. The stream runs over the intruded mass; and where the latter terminates, and the sandstones lean against it, the waters leap from the harder to the softer rock, immediately beside the quiet parish burying-ground, in a cascade of some eight or ten feet. From this point, for a full mile downwards, we find an almost continuous section of the sandstone--stratum leaning against stratum--in an angle of about thirty. The portion of the system thus exhibited must amount to many hundred yards in vertical extent; but as I could discover no data by which to determine regarding the space which may intervene between its lowest stratum and the still lower beds of Carmylie, I could form no guess respecting the thickness of the whole. In a bed of shale, about a quarter of a mile below the village, I detected several of the vegetable impressions of Carmylie, especially those of the grass-weed looking class, and an imperfectly preserved organism resembling the parallelogramical scale of a _Cephalaspis_. The same plants and animals seem to have existed on this high platform as on the Carmylie platform far beneath. A little farther down the course of the stream, and in the immediate neighborhood of the old weather-worn tower of the Ouchterlonies, there occurs what seems a break in the strata. The newer sandstones seem to rest unconformably on the older sandstones which they overlie. The evening on which I explored the course of the Elliot was drizzly and unpleasant, and the stream swollen by a day of continuous rain, and so I could not examine so minutely as in other circumstances I would have done, or as was necessary to establish the fact. In since turning over the _Elements_ of Lyell, however, I find, in his section of Forfarshire, that a newer deposit of nearly horizontal strata of sandstone and conglomerate lies unconformably, in the neighborhood of the sea, on the older sandstones of the district; and the appearances observed near the old tower mark, it is probable, one of the points of junction--a point of junction also, if I may be so bold as venture the suggestion, of the formation of the _Holoptychius nobilissimus_ with the formation of the _Cephalaspis_--of the quartzose conglomerate with the Cornstones. In my hurried survey, however, I could find none of the scales or plates of the newer ichthyolite in this upper deposit, though the numerous spherical markings of white, with their centrical points of darker color, show that at one time the organisms of these upper beds must have been very abundant.