PART 4.] Foote: Geoloffy of North Arcot District. 
nan’OAV ridge lying noi’tli-east of tlie village of Narnavaram, and not to be con¬ 
founded with the Narnavaram peak, Avhich forms dhe southern end of a large 
outlier which includes the Saddashemallai or Sathuskonda, the highest member 
of the Nagari group, and the mountains south of Kdlabastri (Calaetsy). The 
fourth large outlier includes the Ransagiri and the Kambakam (Cumbaucum) 
Drug mountains. 
Many of the quartzite beds Avhich rest on the gneiss in marked unconformity 
are coarsely conglomeratic, including pebbles of gneiss. 
Petrological characters. occasionally of ribbon jasper. The quartzites 
are generally very massive, and semi-vitreous in texture, and occur in thick beds 
which often show but little lamination. The sui-face of .some of the beds as often 
covered thickly Avitli small annular markings, as if they had been stamped all over 
with an ordinary wad-enttor. No satisfactory explanation of the cause of these 
markings had yet been offered. In some beds the rippling caused by current 
action has been beautifully preserved. 
The prevalent colors of the quaidzites arc pale greys and drabs, all weathering 
to shades of buff or pale orange. The principal lines of scarp face the south, e. cj., 
those of the Nagari Nose, the Narnavuiram peak, the Saddashemallai, and the 
Tripatti mountains, but very fine east and west scarps are seen on the Ransagiri. 
The three scaiqis first mentioned are in many parts quite vortical, and form per¬ 
fectly bare walls of rock from a few hundred to over a thousand feet in height. 
The smaller outliers show some of the loAvest beds, but arc of no special interest. 
The whole of the beds exposed in the North Arcot district belong to the 
second lowest of the divisions recognized in the Kadapa series by Mr. King' and 
called by him the Nagari series, a yet lower series underlying the Nagari bods 
having been recognized by him further north near the Pa 2 Aagni river in Kadajja 
district. 
The most southerly recognized outcroj) of the KadajAabeds is the Nagari Nose 
mountain, but it is not improbable that some largo detached masses of quartzite 
occurring at the base of the Gondwana rocks at Naikenpalem, eight miles further 
south-east, ought to be regarded as relics of the basement bed of the Nagari 
group. These masses of quartzite will be referred to again further on. 
The Upper GoNDW.4ifA Series, Rajmadal Group. 
The great series of rocks knoAvn under the name of the Upper Gondwana, 
which occupy a very imjiortant position in the northern half of the peninsular 
area, are represented in the Madras region by considerable formations of great 
interest, because tliej’’ contain fossil plants, some of which are identical with those 
occurring in the Ujiiicr Gondwana formations of the Rajmahal hills in Bengal. 
Their reiirosentatives in North Arcot occur in two positions, one norili, 
the other south of the Palar. In the first wo may conveniently distinguish 
three localities, the Sattavedu, the Alikur (Alcoor), and the Pyanur areas ; in 
the second there are some twenty-five small patches scattered widely over the 
surface of the gneissic area in the Arcot taluq, a few miles south-west of Con- 
' See Memoirs Geological Survey of India, Vol. VIII. 
