The engraved rocks, on the contrary, must be of some antiquity; that is to say, they must certainly date from a time before the influence of Europeans was much felt in Guiana. As has already been said, the engravings are of two kinds and are probably the work of two different people; nor is there even any reason to suppose that the two kinds were produced at one and the same time. These two kinds of engraving may, for the sake of convenience, be distinguished as ‘deep,’ [a typical example of which is in Figure 2] and ‘shallow’ [typical example Figure 3,] respectively, according as the figures are deeply cut into the rock or are merely scratched on the surface. The former * * vary from one-eighth to one-half of an inch, or even more, in depth; the latter are of quite inconsiderable depth. This difference probably corresponds with a difference in the means by which they were produced. The deep engravings seem cut into the rock with an edged tool, probably of stone; the shallow figures were apparently formed by long continued friction with stones and moist sand. The two kinds seem never to occur in the same place or even near to each other; in fact, a distinct line may almost be drawn between the districts in which the deep and shallow kinds occur, respectively; the deep * * form occurs at several spots on the Mazeruni, Essequibo, Ireng, Cotinga, Potaro, and Berbice Rivers. The shallow form has as yet only been reported from the Corentyn River and its tributaries, where, however, examples occur in considerable abundance. But the two kinds differ not only in the depth of incision, in the apparent mode of their production, and in the place of their occurrence, but also--and this is the chief difference between the two--in the figures represented. * * * * * They (the shallow engravings) seem always to occur on comparatively large and more or less smooth surfaces of rock, and rarely, if ever, as the deep figures, on detached blocks of rock, piled one on the other. The shallow figures, too, are generally much larger, always combinations of straight or curved lines in figures much more elaborate than those which occur in the deep engravings; and these shallow pictures always represent not animals, but greater or less variations of the figure which has been described. Lastly, though I am not certain that much significance can be attributed to this, all the examples that I have seen, face more or less accurately eastward.