gorge was followed, as most authors absorb the work of others without verifying it throughout. In this matter even the present writer, in the beginning of these investigations (1881), partially 
Fig. 10.—Map of the Whirlpool Ravine. bb, Position of section (Fig. 11). accepted Lyell's idea, but distinctly showed that the buried ravine from the whirlpool was not preglacial but probably that of a small interglacial stream, and not that of the Niagara River. Prof. Claypole found rocks in the ravine, and then the writer immediately corrected his statements (1887), and later explained the whole history; but apparently Prof. Gilbert had forgotten these observations and went back to Lyell's views in their entirety. The mistake was easily corrected by going through the ravine, where rocks three hundred feet above the bottom of the river are exposed, as shown in Figs. 10 and 11. The exposed rocks along the western side of the ravine show the slope as in section, which is a characteristic form of ancient valleys in contrast to the vertical walls of the cañon (Figs. 6 and 7), while on the eastern side the rocks are covered with drift and landslides, but at the same time demanding sloping walls beneath. Thus the presence of rocks so high in the ravine removes from the calculations of the work of the river the obstructions of early observers, and relegates the hamlet of St. Davids, made famous the world over, to its peaceful repose.
It is perhaps necessary to explain the form of the whirlpool basin. A moderately shallow valley, now buried, was formed in 
Fig. 11.—Section across the Whirlpool Ravine: located at bb (Fig. 10). ancient times by a stream flowing from near the railway bridges, and extending down by way of the buried ravine (which has given so much trouble) to join the ancient Tonawanda River a little to the west (see Fig. 5). Most of the capping limestones in the ancient little ravine near the site of the whirlpool had been removed, leaving at or near the surface only soft, shaly rocks, yet three hundred feet above the bottom of the river. When the modern falls had receded so as to reach the edge of the little buried valley, it found the surface occupied by loose materials which for a short distance the river easily swept out, and thus by the cir-
