438 Capt. Cullen's Notice of the Geological Features 



tufa in nodules, or blocks, of from six to eighteen inches dia- 

 meter, extremely hard, and of a dirty white or gray colour, as 

 if from an intermixture of clay. They were very vesicular in- 

 ternally, and externally covered with hard, knotty, irregular- 

 shaped protuberances, which were of a size proportionate with 

 that of their respective nuclei. They were used, loosely piled 

 together, to form inclosures. 



This variety of calc-tufa was met with frequently afterwards, 

 and in great abundance ; but I never had a good opportunity 

 of examining it in situ. 



In the banks of a nulla between Cuddapah and Chinnoor, 

 as also in the bank of the Pennar at the latter village, I had 

 a transient view of it in the mass ; and it there appeared to 

 form a horizontal stratum of two or three feet in thickness, a 

 few feet below the surface. 



Flinty slate and hornstone still remain for notice. I have 

 mentioned the appearance of the latter at Curcumbaddy, in 

 contact with the clay-slate ; and the only recurrence of it that 

 I recollect, possessing decidedly the character of that rock, 

 was at the village of Yenapilla, three or four miles south-east 

 of Nundaloor, where it appeared in large globular blocks, very 

 much intersected by veins of quartz, over a space of four or 

 five square miles. The flinty slate was much more abundant, 

 being found interstratified with the clay-slate almost every 

 march from Curcumbaddy to Wuntimettah. 



The colour and texture of the hornstone were generally 

 very uniform in each situation ; but the flinty slate was fre- 

 quently very much veined with different shades of gray or 

 blue. The strata were sometimes, however, perfectly uniform 

 in their colour, being occasionally of a dark blue, at other 

 times of a light gray, and externally strongly resembling the 

 dark blue limestone of the district of Cuddapah. 



These were the principal rocks that occurred in the clay- 

 slate of the second division. 



Besides varieties of all the rocks hitherto enumerated, se- 

 veral others will be found amongst the specimens forwarded, 

 which the limits proposed for this paper will not admit of de- 

 scribing at present. 



The third division, or compact blue limestone, will easily 

 be disposed of, as it occupies the whole of the flat country, 

 extending from the Nulla Mulla range to Banaganapilly, to 

 the exclusion of every other rock. Its texture within this tract 

 was tolerably uniform, but it exhibited a considerable variety 

 of colour; near the Nulla Mulla hills it was generally of a 

 dull lead gray, and this variety, on fracture, presented a fo- 

 liated appearance; about Jell ila, and particularly in the bed 



of 



