22 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [DoC. 9, 



15 feet; it is entirely excavated in granular massive gypsum or 

 alabaster, veined with blue and grey stripes and occasional patches 

 of clay, the whole being apparently a solid mass. The watercourse 

 was nearly dry on the 9th of April, only a few of the pools below 

 the places where there are small waterfalls in flood-time being 

 filled with small quantities of intensely salt and bitter water, so that 

 it could be easily followed on foot. "We traced it up for about 

 1 J miles, making a very tortuous course, when the cliifs appeared to 

 be getting somewhat lower ; but there was no sign of the gully com- 

 ing to an end as far as could be seen from the highest point reached. 

 The bottom of the valley is eroded into a smooth and nearly semi- 

 circular channel by the rush of the winter torrents, either in the 

 solid rock or in large tumbled blocks ; while, just above the flood- 

 level, the side cliiFs are scored into parallel grooves resembling the 

 fluting of an Ionic pilaster, by the action of water charged with sand 

 trickling down from above. These grooves are about half an inch 

 deep, separated from each other by small sharp-edged ridges. They 

 are, as a rule, vertical, and in the direction of the flow of the water ; 

 and they always end, in the most striking manner, just at the high- 

 water-line. 



At intervals all along the valley an old alluvium of gravel and 

 sand with fragments of gypsum, the last being exceedingly rough and 

 irregular in outline, is seen at heights of between 50 and 70 feet. 

 This gravel has been eroded into steep cliffs. The alabaster occur- 

 ring in this valley somewhat resembles that of Chellaston and Eauld, 

 in Staffordshire, but without the red veins, being only mottled with 

 blue or grey bands of clay instead. The best blocks seen, lying loose 

 on the watercourse and tumbled from the cliffs, cubed about 4 feet 

 on the side ; but it would be difficult to find one of this size perfectly 

 sound, though there are many places where large masses might be 

 got by quarrying. The semitranslucent variety of alabaster, such as 

 that of Yolterra, does not occur here ; but nodules of a somewhat si- 

 milar character were observed in the dark shales further to the 

 north. 



Gypsum of Gharandel. — In the lower part of Wady Gharandel the 

 same gypsum-marls appear, in hills of considerable height, say from 

 300 to 400 feet. The principal feature is formed by a massive bed 

 of opake-white gypsum, overlying dark bluish-green and gray marls 

 and clays filled with selenite in fibrous masses, and occasionally in 

 detached crystals. The large bed breaks up and falls, from the slip- 

 ping away of the marl below it ; but the tumbled blocks are mostly 

 reconsolidated by the action of water, forming reconstructed beds on 

 the slopes of the shales, which are again subjected to denudation, 

 giving rise to hills of extremely irregular outline and structure. The 

 whole of the surface of the slopes, especially the more prominent, is 

 very rough and uneven, owing to the solvent action of atmospheric 

 water on the gypsum. The more impure and sandy portions, which 

 resist the weather better, form regular saw-backed crestings, so 

 that the process of climbing the hills, in spite of their being mainly 

 made up of clay, is disagreeably like going along a garden-wall 



