62 LA TOUCHE : GEOLOGY OK WESTERN RAJPUI ANA. 



about 30 , away from the large mass of granite forming the eastern por- 

 tion of the hill towards Ludrara. The granite and rhyolite are here ia 

 contact, the former as usual sending off numerous veins into the 

 latter. The rhyolites are of the ordinary porphyritic type, occasionally 

 containing large crystals of red felspar. Close to the granite on the 

 north-west side a thick band of pebble beds and breccias is inter- 

 stratified with the rhyolites. The contact of these beds with the 

 granite is concealed by sand. 



Another exposure of the pebble beds occurs in a small hill rising to 

 927 feet, close to the village of Siner, about 10 miles to the west of 

 Siwana. At the base are some rhyolites with flow-structure succeeded 

 by strongly porphyritic rhyolite. These are exposed at the south-west 

 side of the hill close to the village. Upon them rests a bed of a dark 

 greenish rock of basic type, portions of which are amygdaloida!. 

 Then comes a band of conglomerate in which the pebbles are well 

 rolled, consisting of rhyolites of various types, some showing good flow- 

 structure, and a few of quartz. This band is about five feet thick and 

 is succeeded by a band of highly vesicular rhyolite of a dark greenish 

 colour, and on top of all a thick flow of rhyolite of the ordinary^ por- 

 phyritic type. All these beds dip to the north-east at an angle of 

 about 35 . A diagrammatic section of the hill is given in fig. i, 

 PI. IV. The pebble bed can be traced all round the western side of the 

 hill, and appears again in a smaller hill about a quarter of a mile away 

 to the north. Here besides the pebbles of rhyolite and quartz it contains 

 a few, also well rolled, of a micaceous gneiss or gneissose granite. 



A dyke of rather coarse grained dolerite, 30 feet wide, breaks 

 across the larger hill through the rhyolites and conglomerate band, 

 striking from south-east to north-west. On the southern side of the 

 hill it runs parallel to the bedding of the rhyolites and conglomerate 

 for a short distance, just beneath the latter, and divides into two 

 branches as shown in the section. It also appears on the same strike in 

 the smaller hill to the north. 

 ( 62 ) 



