part 1 .] Blanford: Great Indian Desert between Sind and Rajput, and. 13 
alluvial plain. In this plain between one and two miles east-north-east of the fort, shale, 
pale-greenish and dark-red in colour, is found in wells. The relations of this shale are 
obscure; it may belong to the sandstone group. 
III.— Route from Jodhpur to Rohri via Pokran. 
Jodhpur to Pokran .—On the road leaving Jodhpur in a west-north-west direction red 
sandstones are seen at intervals as far as Lowo, a distance of 80 miles. Two small exposures 
of Malani beds were observed near Jodhpdr, one near the village of Pair!, eight miles north 
of the town, the other in a stream-bed, 4 miles farther north, near Managra. The sandstones 
are well seen to beyond Tiyuri, 20 miles north-west of Jodhpur, rising into low hills : and 
similar rises extend nearly twice as far in a direction a little north of west; but from Tiyuri 
to Lowo rocks .ire only seen at rare intervals, the country consisting of sandhills with broad 
sandy flats intervening between them. The sandhills continue for about 40 miles, and then 
gradually becomes lower, less extensive, and more distant from each other, until they finally 
disappear between Dechu and Mandlo. They have no definite arrangement in ridges, but 
present, as usual, steep scarps to the north-east. 
It is impossible to say whether the Jodhpdr sandstones continue throughout the area 
beneath the sand. They appear here and there, and the only other rock seen was some shale 
of a greenish colour which is exposed in a tank just west of Dechu, 60 miles from Jodhpur, 
and may belong to some beds better seen at Lowo. Beyond Mandlo the country is very flat, 
and some portions, which appear to be depressed below the general level, form salt plains. 
Three of these are passed between Mandlo and Pokran, one at Daidia, a second north of 
Lowo, and the third, which is by far the largest, a few miles east of Pokran. The origin of 
these plains is very obscure : they may have originated in changes of level, though there is a 
possibility of their being portions of old valleys dammed up by sand. When rain falls, water 
accumulates in them to a small extent, a.nd, evaporating, leaves a thin crust of salt. Similar 
salt plains were seen near Redano hill, west of Balmir. The amount of denudation from 
raiu in this region must be singularly small, or such shallow depressions would be filled up. 
The red Jodhpur sandstone is seen east and west of the Daidia plain, and it forms a 
continuous low scarp to the north of the plains at Lowo and Pokran. But at Lowo itself 
some peculiar gritty and sandy shales are seen, mostly hard and sometimes porcellanic, of 
various shades of red and green, and containing in places pebbles and boulders of all sizes up 
to many feet in diameter, composed of felstone porphyry and granitoid syenite, all apparently 
derived from the Malani beds. These shales stretch across towards Pokran, where they occur 
to the south and west of the town. About half way from Lowo to Pokran there is a con¬ 
siderable outburst of basalt, the relations of which are not clear, no similar rock having been 
found associated with the volcanic Malani beds. 
The town of Pokran appears to be built upon sandstone, but the rock is badly seen, and 
is cut up by veins of calcareous tufa. To the north the same rock forms a low' escarpment: 
whilst south, west, and south-east of the town volcanic rocks occur, clearly belonging to the 
Malani porphyries, and consisting of felsite of various colours, often pale-green or slate-coloured, 
with, in places, grains of transparent quartz and the characteristic felspar crystals. In many 
places these rocks have a distinctly stratified appearance, due probably to imperfect cleavage. 
Upon the volcanic rocks rests, in places, a thick deposit of boulders derived from them, 
in a matrix of coarse red grit. Green shales, precisely like those of Lowo, are associated with 
this boulder bed, which contains rounded fragments of all sizes up to two feet in diameter. 
At one spot, a short mile south-weBt-by-west of Pokran, where the surface of the porphyry, 
underlying the boulder-bed, was exposed, it was unusually smooth and distinctly striated, the 
