GEOLOGY OF CENTRAL INDIA. 



71 



beds. A very common appearance throughout the whole of Central 

 India is derived from this source. I allude to the occurrence of a thin bed 

 of quartz, seldom more than a few feet in thickness, often only a few inches, 

 which runs along the ridges of the hills throughout the whole extent, form- 

 ing a sharp angle from which the darker colored argillaceous schists slope 

 on either side. Where the quartz beds are thicker, they often rise 

 abruptly to the right and left on rugged, nearly perpendicular cliffs — often 

 presenting the appearance of ruined fortifications and castellated walls 

 rising from the slope of the hills, and exhibiting altogether the most strik- 

 ing scenes which I have ever witnessed. Numerous perpendicular cliffs 

 also present themselves — ^the perpendicular face of these cliffs, being on 

 the opposite direction to that on which the strata dip. This is particu- 

 larly observed in hills formed of the distinctly stratified quartz rock, 

 described in pages 80 and 81, and even more strikingly so, when the 

 above rock alternates with argillaceous schist, and on the direction in 

 which the strata dip the hills are often almost destitute of soil, the 

 sun being reflected from the bare surface with fearful intensity, while 

 on the other side the slope, especially in such cases, when the out- 

 croppings of argillaceous schist are observed, is covered with jungle, 

 above which the cliffs just described, are seen rising abruptly. The 

 ridge-shaped hills are, however, the most common, and these are gene- 

 rally formed of distinctly stratified quartz, the strata being arranged in a 

 nearly vertical position. From the sharpness of the angle and the regu- 

 larity of the outline which the summits of many of these hills present, — 

 these summits appear in the distance to be fiat, and the deception is in- 

 creased by their frequently assuming the form of a truncated cone. In 

 the latter instance the sharp ridge still exists. It is continued for some 

 distance in a direction parallel to the horizon, and then suddenly slopes on 

 either side at a very acute angle. We have also denticulated ridges, the 

 hills exhibiting this appearance being generally composed of siliceo- 



