=Geology of the Aravallis.=—The general character of the Aravalli is its primitive formation:[1.34] granite, reposing in variety of angle (the general dip is to the east) on massive, compact, dark blue slate, the latter rarely appearing much above the surface or base of the superincumbent granite. The internal valleys abound in variegated quartz and a variety of schistous slate of every hue, which gives a most singular appearance to the roofs of the houses and temples when the sun shines upon them. Rocks of gneiss and of syenite appear in the intervals; and in the diverging ridges west of Ajmer the summits are quite dazzling with the enormous masses of vitreous rose-coloured quartz. The Aravalli and its subordinate hills are rich in both mineral and metallic products; and, as stated in the annals of Mewar, to the latter alone can be attributed the resources which enabled this family so long to struggle against superior power, and to raise those magnificent structures which would do honour to the most potent kingdoms of the west. The mines are royalties; their produce a monopoly, increasing the personal revenue of their prince. _An-Dan-Khan_ is a triple figurative expression, which comprehends the sum of sovereign rights in Rajasthan, being _allegiance_, _commercial duties_, _mines_. The tin-mines of Mewar were once very productive, and yielded, it is asserted, no inconsiderable portion of silver: but the caste of miners is extinct, and political reasons, during the Mogul domination, led to the [13] concealment of such sources of wealth. Copper of a very fine description is likewise abundant, and supplies the currency; and the chief of Salumbar even coins by sufferance from the mines on his own estate. _Surma_, or the oxide of antimony, is found on the western frontier. The garnet, amethystine quartz, rock crystal, the chrysolite, and inferior kinds of the emerald family are all to be found within Mewar; and though I have seen no specimens decidedly valuable, the Rana has often told me that, according to tradition, his native hills contained every species of mineral wealth. =The Patār Plateau.=—Let us now quit our alpine station on the Aravalli, and make a tour of the _Patar_, or plateau of Central India, not the least important feature of this interesting region. It possesses a most decided character, and is distinct from the Vindhya to the south and the Aravalli to the west, being of the secondary formation, or trap, of the most regular horizontal stratification. The circumference of the plateau is best explained in the map, though its surface is most unequally detailed, and is continually alternating its character between the tabular form and clustering ridges.