164 
EXPLORATIONS IN TURKESTAN. 
pink, and the brown — is not exact, for while certain parts are composed of true sand, 
small portions are shaly, and large parts are composed of very fine material, which 
is neither sand nor clay, bnt a sort of silt which often reseml)les loess. Tlie bedding 
is very even at the hone, but signs of subaerial deposition make their appearance 
below the middle of the pink beds. At first there are sun-cracks and ripple-marks, 
then thin lenses of a slighly different texture from the surrounding rock, and 
finally in the brown sandstone veiy distinct stream channels filled with fine gravel. 
Throughout the Tertiary series, from the limestones upward, the layers are discon- 
tinuous; at any given point the bedding seems horizontal and unbroken, yet if 
individual beds are traced for some distance they gradually die out. 
Fig. 123. — Ripple-marks on the lower half o( the pink sandstone near Kan Su, west of ICashgar. 
The conditions under which the Mesozoic-Tertiary series were deposited seem 
to have been largely subaerial, or at least non-marine. The coarse conglomerates 
at the base probably indicate arid or semi-arid conditions in a region of considerable 
relief. As relief grew less, or as the climate grew moister, the gravel of the con- 
glomerate gave place to sand and that in turn to shale ; in the latter are four or five 
coal seams. The next period, that of the vennilion beds, seems to have opened at 
a time of subaerial deposition when the conglomerates and the cross-bedded .sand- 
stones were fonned; but toward the end the encroachment of the sea is indicated 
by the deposition of the marls and fossiliferous limestones. Elsewhere throughout 
the whole Mesozoic-Tertiary series fossils seem to be wholly absent, although the 
deposits are well fitted to preserve the remains of plants and animals if any had 
