Petroglyphs have seldom been found in the central area of the United States. In the wooded region of the Great lakes characters have been depicted upon birch bark for at least a century, while in the area between the Mississippi river and the Rocky mountains the skins of buffalo and deer have been used. Large rocks and cliffs favorably situated are not common in that country, which to a great extent is prairie.
In the general area of these typical groups characters are frequently found which appear intrusive, i. e., they have a strong resemblance not only to those found in other American groups, but are nearly identical with characters in other parts of the world. This fact, clearly established, prevents the adoption of any theory as to the authorship of many of the petroglyphs and thwarts attempts to ascertain their signification.
Ensign Albert P. Niblack, U. S. Navy, (_a_) gives a brief account, with sketches, reproduced here as Fig. 4, of petroglyphs in Alaska, which were taken from rocks from the ancient village of Stikine, near Fort Wrangell. Others were found on rocks just above high-water mark around the sites of ruined and abandoned villages.
[Illustration: FIG. 4.--Petroglyphs in Alaska.]
In the upper character the Alaskan typical style of human faces is noticeable. The lower gives a representation of the orca or whale killer, which the Haida believe to be a demon called Skana, about which there are many mythic tales. Mr. Niblack remarks:
In their paintings the favorite colors used are black, light green, and dark red. Whether produced in painting, tattooing, or relief carving, the designs are somewhat conventional. However rude the outline, there are for some animals certain conventional signs that clearly indicate to the initiated what figure is meant. With the brown bear it is the protruding tongue; with the beaver and wolf it is the character of the teeth; with the orca, the fin; with the raven, the sharp beak; with the eagle, the curved beak, etc.
Mr. G. K. Gilbert, of the U. S. Geological Survey, gives the following information concerning petroglyphs observed by him in the vicinity of San Francisco mountain, Arizona:
The localities of the sketches Figs. 5, 6, and 7 are about 35 miles east and southeast of San Francisco mountain, the material being a red sandstone, which stands in low buttes upon the plain. About these are mealing stones, fragments of pottery and chipped flints, giving evidence of the residence of sedentary Indians. So many localities of petroglyphs were seen that I regard it as probable that a large number could be found by search. The drawings in every case but one were produced by blows upon the surface of the rocks, breaking through the film of rock discolored by weathering so as to reveal (originally) the color of the interior of the rock. The single exception is the first pattern in Fig. 6, similar to the patterns on pottery and blankets, produced by painting with a white pigment on red rock. The original arrangement of the drawings upon the rock was not as a rule preserved, but they have approximately the original arrangement. I neglected to record the scale of the drawings, but the several pictures are drawn on approximately the same scale.