National Geographic : 1892 May 15
146 C.W. Hayes-Expeditionthrough the Yukon District. have been concealed from us by the clouds which hung about their summits. Recent volcanic Activity. The most striking effect of recent volcanic activity in this region is the wide-spread deposit of volcanic ash, or tufa, which covers the southeastern portion of the Yukon basin. This deposit was first noted by Schwatka in his reconnaissance of 1883. It was more fully described as it occurs on the Pelly and Lewes by Dawson in his report of the Yukon expedition of 1886, and was noted by McConnell in 1887 and Russell in 1889 on the Yukon and Lewes. It was first seen by our party on Teslin river shortly after leaving lake Ahklen, and from this point northward it forms a conspicuous and nearly continuous white band in cut banks of the river nearly down to Selkirk, at the confluence of the Lewes and Pelly. Where first seen the layer of tufa was less than an inch in thickness, and from this increased to a maxi mum of nearly a foot near the mouth of the Teslin, with some local accumulations of two or three feet. The alluvium which has accumulated upon the layer of tufa is generally about a foot in depth, but it occasionally varies from nothing to three or four feet. A foot, however, probably represents the normal accumulation of soil under the prevailing conditions since the deposit of the tufa. The first point at which the tufa was noticed in the White River basin was about one hundred miles southwest of Sel kirk, on the divide between the Nisling and Donjek, eastern tributaries of White river. It is altogether probable that the deposit was continuous over the whole of this country, but no localities favorable for its preservation and display were seen on the high land traversed. A layer much heavier than that ap pearing on the Lewes would in a short time be wholly lost on a surface almost entirely destitute of soil and composed of rock fragments of varying degrees of coarseness. In the banks of the Kluantu and Donjek the tufa does not form a distinct layer as along the Lewes, but is probably repre sented by certain stratified beds of white sand, which were re garded at the time as lake deposits. They are indistinguishable from the sediments carried and deposited by the river at the present time, except in being somewhat coarser.
1893 Feb 08
1892 Mar 31