WYSORE 91 lower, and so on all down the course of the stream at short intervals. These tanks, varying in size from small ponds to extensive lakes, are dispersed throughout the country to the total number of 37,682 ; and to such an extent has this principle of storing water been followed, that it would now require some ingenuity to discover a site suitable for a new one. The largest of these tanks is the SULEKERE, 40 miles in circumference. The spring heads, called trrargis, form an important feature of the hydrography of the north-east. They extend throughout the border regions situated east of a line drawn from Kortagiri to Hiriyúr and Molkalmuru. In the southern parts of this tract the springs may be tapped in the sandy soil at short distances apart, and the water rises close to the surface. Northward, the supply is not so plentiful. When the water is obtained, it is either conducted by narrow channels to the fields, or a well is constructed, from which the water is raised by bullocks. Geology.--The geological structure of Mysore is mainly hypogene schists, penetrated and broken up by plutonic and trappean rocks in every form of intrusion, and overlaid with occasional patches of laterite and kankar (calcareous deposits), and, to the north of the main axial line, with black cotton-soil. The granitic upheavals are seen either in precipitous dome-shaped monoliths, in low steppes, or in undulating layers, separated by fissures and joints, so as to present alniost a stratified appearance. Detached cuboidal masses may be observed, not only weathering by concentric exfoliation into spheroids on a large scale, but assuming in their decay most fantastic forms. The prevailing granite is composed of quartz, felspar, mica, and hornblende, in varying combinations; but we also find syenite, protogine, peginatite with its resulting kaolin, and porphyritic, hypersthenic, and anygdaloidal granites, with serpentine in eruptive masses, or in dikes and veins. Trappean rocks in the form of basalts, greenstone, felstone, and felstone porphyries, with other combinations, are to be seen similarly penetrating the gneiss; and mica and chloride schists in disrupting or intrusive masses, in low dikes, and extensive overflows. The earth, resulting in the shape of an open loam, varying in colour from a light red to dark chocolate, is not only highly fertile, but overlays the altered gneiss, etc., in such a way as to ensure excellent drainage. The long low dikes are numerous round Bangalore, and at the head-waters Arkávati valley, where their intrusion is greatest, and where their decay by concentric exfoliation and lamination may be distinctly traced. Solid veins, too, may be observed running through the isolated granitic drugs which form so striking a feature of the country, and around the bases of which fallen portions from the bare summits present singular masses of amorphous forms.
