originated from deposition in water. Many a battle was fought in this locality, and not a few of the trap-dykes and hills possess to the geologist a classic interest, from having been the examples whence some of the best established geological opinions were first deduced. The contest between the Huttonians and Wernerians terminated long ago in the acknowledged victory of the former; Hutton's doctrines are now recognised all over the world. It is interesting, however, to walk over the scenes of the warfare, and mark the very rocks among which it raged, and from the peculiarities of which it took its rise. Basalts and greenstones, sandstones and shales, with all their crumplings and contortions, still stand up as memorials of powerful igneous action, and of physical changes in the primeval past; and they have become to the geologist memorials, too, of changes in the onward progress of his science, where, out of conflicts perhaps yet more tumultuous than those of ancient Nature, there emerged at last the clear demonstrable truth. [Illustration: Fig. 34.--Intrusive Trap.] In the accompanying section (Fig. 34), the more marked characters of intrusive traps are exhibited. The main mass of igneous rock is the dyke (_d_), rising through a dislocation or fault, which has thrown down the beds on one side several feet below those on the other, as is shown by the interruption of the shale and ironstone beds (_sh_). The dyke gives off two ramifications, one of them cutting across the beds obliquely as a vein (_v_); the other passing along the planes of the shaly layers as a horizontal bed (_b_). The vein, it will be noticed, produces considerable alteration in its progress, carrying up and baking a portion of the shale (_sh_), and turning up the edges of the beds on both sides, which get cracked and hardened along the line of contact. The bed runs with some regularity for a short distance through the shales, which show marks of great alteration at their junction with the trap. Its under surface at one point is seen to have involved a portion of the shale which has become in consequence highly metamorphosed, while along the upper surface the bed has sent out a short irregular vein that twists and otherwise alters the shales above. These circumstances would suffice to show that even though we did not find this bed in connexion with a mass of intrusive trap, it must, nevertheless, have been thrust among previously-formed strata, and could not have been contemporaneous, that is, poured out along the sea-bottom before the shales above it were deposited.