86 
Records of the Geological Survey of Lidia. [vol. x. 
Byana hills, thick bands of conglomerate. -Ripple-markings and sun-cracks are common and 
are particularly well seen in the Alvvar fort hill. An arkose is of frequent occurrence at the 
base of the Alwar quartzites, where they rest upon the gneiss. 
The best seotion of the junction of the Alwar quartzites and the gneiss is exposed 
near Tatra. South oi the road leading to Tatra the granitic gneiss occurs at the base 
of the ridge, and upon this rests a lifigularly bedded coarse quartzite dipping at a high 
angle to the west. North of the road some additional beds come in between the gneiss and 
the quartzites. Resting directly on the gneiss is a band of conglomerate about two feet 
thick, composed principally of rolled pebbles of quartz; upon this there is a considerable 
thickness of the arkose, the materials of which were apparently derived from the gneiss; 
this passes up gradually into the ordinary quartzites of the scries. Other sections shewing 
the unconformity between the two series are exposed near Garhi a few miles east of Tatra, 
and near the southern end of the Tatra ridge at Sabraoli, as well as in the Lalsot hills at 
Geesgarh. 
In places the arkose rock has been re-metamorphosed to such an extent that when Dot 
seen in connection with the gneiss below, or the quartzites above, it is difficult to tell it from 
the true gneiss. Instances of this occur in the hills round Harsora, which are formed of 
obscurely bedded gneiss, but from their being isolated on the plain (the only rock near is a 
ridge of quartzite about half a mile to the south) I am unable to say to which series they 
belong. At Dodikar, a few miles north-west of the town of Alwar, where the arkose rocks 
are well developed, they form a circle of hills, in the centre of which the rocks are covered 
by the alluvium, blown sand, &c. The arkose at the base of the hills is highly crystalline 
and as gneissose as that of the Harsora hills, but here they pass up gradually into the 
quartzites which cover them. Other sections of the arkose rocks passing into the quartzites 
are met with at Palpar, Baggeri, Kbertal and Pahari. 
The best sections of the Alwar quartzite are to be seen in the Byana hills, where an 
enormous thickness of them is exposed, as they are less disturbed and altered than elsewhere, 
for although they are a good deal twisted along the strike, they scarcely ever dip at a higher 
angle than 20°. At Byana the strike is north-east to south-west; but at Badalgarh, a short 
distance west, it changes to west-north-west, east-south-east; and at Hathoree, about twelve 
miles further west, it again becomes north-east to south-west. 
In these hills the lowest members of the Alwar group (the Raialo quartzite and lime¬ 
stone) are absent, and the group consists principally of quartzites, shales, thick bands of 
conglomerate, and contemporaneous trap. Overlap occurs among the quartzites, and there 
are two cases of local unconformity. 
The Alwar group in the Byana hills rests uuconformably upon the schist series. The 
unconformity can be well seen at Nitbahar, where the quartzites rest upon the edges of the 
nearly vertical schists, consisting of alternations of argillaceous and quartz schists, and with 
a thin band of conglomerate seldom more than a foot thick between them. Other sections of 
the unconformity are exposed a few miles further west. 
The Alwar quartzites in these hills can bo divided into several sub-groups well marked 
by overlap or local unconformity : 
Weir—quartzites and black slatey shales. 
Damdama—quartzites and conglomerate. 
Byana—white quartzite and conglomerate. 
Badalgarh—quartzite and shale. 
Nithahar—quartzites and bedded trap. 
