58 PASCOE: GEOLOGICAL NOTES ON MESOPOTAMIA. 



zone ;t c " is exposed in a very broad flat anticline pitching im- 

 perceptibly south-eastwards ; it contains a few thin conglomerate 

 bands. 



The Conglomeratic stage is finely exposed in the prominent 

 scarp of the Jabal Nasaz, and in fact constitutes this range. The 

 actual conglomerate zone, zone " d," as I have called it, reaches a 

 greater thickness here (exaggerated in the section) than in any other 

 locality so far visited, attaining 400-500 feet ; this zone I have 

 designated the " Nasaz zone." It consists of rapid alternations 

 of conglomerate and subordinate sandstone bands, dipping very 

 gently in a north-eastern direction, and producing precipitous cliffs 

 of some magnitude on the south-west. The dip slope shows the 

 usual intricate dissection and very rounded detail. Amongst the 

 pebbles are numerous pebbles of Fars limestone, measuring up to 

 one foot across. Traced south-eastwards the lower boundary swings* 

 round towards the west and the zone apparently becomes reduced 

 to the size of the Zindanah ridge, and north-west of this, to still 

 smaller dimensions. There appears, therefore, to be great lateral 

 variation in this zone, as in fact in all other zones, of the Kurd 

 series, a" condition typical of a fluviatile deposit. South-west of 

 the Zindanah ridge and forming the shallow synclinal rolling plain 

 of the Dasht-i-Pataki, are brown clays which I have called phase or 

 zone " e " ; they contain a few stringers of gravel. None of these 

 zones can be taken as a definite chronological division ; they are 

 more of the nature of phases which dovetail with one another, and 

 are somewhat difficult to show on a map. 



Alluvium is difficult to distinguish from the massive brown 

 clays of zones " c " or " e," when either of the latter is nearly hori- 

 zontal. 



Structure. 



This area is closer to the origin of the folding movement and 

 shows greater disturbance, than any yet examined. The N.W. — 

 S.E. anticline, beneath which the petroleum primarily collected, 

 became a tightly compressed overfolded isocline similar to others 

 already described. The Fars outcrop must have been very narrow, 

 and ' ridged up ' in the curious way noticed in many neighbouring 

 anticlines, the dip rapidly steepening as the core of the fold was 

 approached. This Fars outcrop, however, was still further narrowed 

 by a large reversed fault which cut out part of the south-western 

 limb. In fact an anticlinal structure cannot now be clearly demon- 



