It is a reproach, I am aware, sometimes cast upon geological researches, that the portion of the earth’s surface exposed to view is as nothing compared with the entire mass, and that another portion, by far the largest segment, is concealed by the ocean, and its own debris. In addition to these disadvantages, it may now be objected that the line of description indicated narrows the field of research still farther, and that a few disconnected materials only are all that can therefrom be extracted. It may be answered,—“That the earth is constructed with such a degree of uniformity, that a tract of no very large extent may afford instances, in all the leading facts, that we can ever observe in the mineral kingdom. The variety of geological appearances which a traveler meets with, is not at all in proportion to the extent of country he traverses; and if he take in a portion of land sufficient to include primitive and secondary strata, together with mountains, rivers, and plains, and unstratified bodies, in veins and in masses, though it be not a very large part of the earth’s surface, he may find examples of all the most important facts in the history of fossils.”[1] We shall, however, along with our lineal descriptions of the mineral kingdom, notice the occurrence, position, and fossil contents of the strata as represented in other parts of the world. CHAPTER II. NATURE AND STRUCTURE OF THE GRAMPIANS. PRIMARY ROCKS. In beginning a description of the earth, every one is prepared for the information, that it must have existed in some form or other antecedent to the development of life upon its surface. Revelation asserts a succession in the objects created, as well as in all the cosmical arrangements connected with the early history of our planet. Things were not perfected at once, and brought simultaneously into adaptation and form; a preparation and a fitting up, as it were, of the inorganic preceded the introduction of the organic structures of creation; and, accordingly, the solid framework of the globe gives corroborative evidence of this anterior condition of its history. The rocks of the period are, from this circumstance, denominated PRIMARY, because they not merely denote the absence, but are assumed to have been formed before the existence, of any types of organic matter, vegetable or animal.