Page:Popular Science Monthly Volume 39.djvu/331

Rh hundred and twenty feet. Near the surface the well penetrated a stratum of basalt, fifteen feet thick. Below this basalt there were alternate beds of clay and quicksand to the depth mentioned, where the sandstone rock was encountered. The well was tubed with heavy iron tubing six inches in diameter, so that there could be no mistake about the occurrence of the image at the depth



stated. The detailed evidence was published by me in the Proceedings of the Boston Society of Natural History for January, 1890. During this last summer, also, I visited the locality and found ample confirmation of it.

In the valley between the Boisé and Snake Rivers, in south-western Idaho, where Nampa is situated, there is an area of several hundred square miles covered with fresh-appearing basalt, which apparently came from vents thirty or forty miles to the east, but in its western flow barely extended five miles beyond Nampa. Below that point there is no lava for seventy miles. The clay and quicksand covering the stratum in which the image was found would seem to have accumulated in the valley of a