charged the next caravan four times as much, though it consisted of the holy pilgrims from Mecca whose acquaintance we found so pleasant.
While stopping with the Khirghiz, we examined several old moraines. It is not necessary to discuss them, for their significance as indicators of pronounced, world-wide changes of climate in the most recent geological times is well known. The most peculiar quality of the Kwen Lun moraines is that they are shrouded in typical loess, a close-grained, yellowish deposit of the finest dust, unconsolidated, and yet so tenacious that for years a perpendicular face will hold the marks of the spade with which it was cut. Wherever the slopes outside the moraines were not too steep, they were likewise shrouded with loess, and wherever there was loess, there was also vegetation. Our first day in the Lop basin happened to be unusually clear, but, as we saw from the Sanju pass, a yellow haze lay low over the desert fifty miles to the north. As the air grew hot, the haze gradually rose and expanded. That night a strong north wind came up. In the morning, as we looked out from our camp among the moraines, the whole country was enveloped in a haze of dust which we at first took for thick, dirty fog or cloud. When the wind died down for a time, the haze began to settle, the mountain tops appeared, and the sky overhead showed a faint bluish tint, though the lower hills, scarcely a mile away, were invisible. When the wind blew again, the dust was whirled upward, concealing the mountains and the sky. We could not see or feel the dust except as a haze, and were only positive as to its nature when the air, forced upward over the mountains by the north wind, became so cool that
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