PLEISTOCENE DEPOSITS OP SEYISTAN 



365 





m^ 



(in» 10 r«i — OrdTei. 



(lA) 27 feet— Plob or bhIuiod Hilt 



(17) fwt— Orovel. 



(15) 20 feet— Grovel, 





(13) 25 feelr-Cruvel. 



a (eet— Bniwn Band. 

 — — Uii«>Q'orn]lty. 



time of the Seyistan volcanoes and exposed in the lacustrine bluffs is 

 shown in the accompan3'ing sections (figures 3 and 4). The main body 

 of the deposits consists of numerous alternations between thick reddish 

 or pinkish strata and thinner strata of a white or greenish color. The 

 pink beds consist largely of clays and 

 very fine silts, which often pass into 

 fine brown sand. Viewed as a whole, 

 the pink layers are very continuous 

 and preserve the same character for 

 mile after mile. In detail, however, 

 they vary considerably, even in short 

 distances. For instance, a layer of 

 clay is often interrupted by a band of 

 fine sand which continues a few hun- 

 dred feet and then dies out. More 

 rarely a layer of grit or fine gravel is 

 exposed, and, rarest of all, a distinct 

 fossil stream bed. Again, in certain 

 places slight unconformities are dis- 

 cernible, as if a little erosion had taken 

 place between the deposition of one 

 layer and the next. Among the more 

 sandy layers there are further evi- 

 dences of exposure to the air. In one 

 place, for intance, the sand shows 

 ripple-marks, worm-casts, and rain- 

 drop prints. Finally, the layers of 

 this formation are everywhere of a 

 reddish tint, varying from pink to 

 brown. The only exception is found 

 in some of the sandier, more quartzose 

 layers, which are gray for a few inches. 

 Everywhere the materials appear to 

 have been exposed to oxidization for a ^^^^^^ ^.-section of ciay Deposits m 

 considerable period under subaerial old Lake Bed of seytstan. 



conditions of such aridity that few or Locality near that of figure 3. Scale: 

 T , ■ J. mi J.1 1 inch = 60 feet. 



no plants were present. Thus, on the 



one hand there was nothing such as a superincumbent sheet of water to 

 prevent decomposition and oxidization, and on the other there was no 

 vegetation to leach out the oxidized iron and prevent the deposits from 

 assuming a red color. Apparently the pink beds were deposited sub- 



II) 10 feel— Bauded browo Qud gnen claS- 



8 fe<'t— PiiiU clay, 



I 20 feet— Pliik clay. 



(7) 14 feel— GrecD clay. 



(6) 23 fee(— PmS clay 



(0) feet — Green clay. 

 (4) 2 feet— Yellow clay 

 (3) 10 feet—PlnIt clay. 



fZi 6 roel— Green clay. 



) feet— Pink cl^y witb sandy lasers. 



iinil 



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