While the condition of the mineral masses in the neighbourhood of Edinburgh furnish interesting illustrations of the structural characters of rocks, such as the columnar, the concretionary, and the fragmentary, &c., the author proposed to confine his remarks at present to what he denominated the FLAWED STRUCTURE.

In the ordinary language of quarriers, the flaws are termed backs, while they are known to masons as dries, and to geologists, when referred to, as slicken-sides. This last term, independent of its provincial character, refers to one peculiar form of the flaw only, and, although explicable according to the same views entertained respecting the origin of the others, is far from being a typical form. The flaw of the lapidary, in reference to crystals or gems, comes sufficiently near in character to justify its adoption.