236 KING: KADAPAH AND KARNUL FORMATIONS. [PART III. 
These quartz-runs and strings are extremely unproductive, there 
No minerals of value being no trace of any mineral ores except small 
iu Mene strings of hard grey specular iron ore. These do 
not occur in sufficient quantity anywhere in the field to have ever been 
worked.: the iron ordinarily: obtained in these districts being from one 
or other of the quartzite groups. 
As a conclusion to this deseription of the Cumbum slates, the 
following notes of Mr. Foote are appended, as he more especially surveyed 
the typical Cumbum area :— 
* From the very great prevalence and the thickness of the surface soil and other 
Mr. Foote’s notes on the  Tecent formations, and the comparative rarity in the valleys 
Cumbum s. and plains of any but well-sections, it would be impossible 
to form any clear and detailed idea of the true sequence of the several minor form- 
ations of slate and quartzite with a few small limestone bands which make up the 
Cumbum sub-group without having surveyed the country in extreme detail and laid it 
down on a large scale. Many of the beds are doubtless frequently reproduced on the 
surface by numerous crumplings, and as in many cases the mineral constitution of a 
bed changes within a few score yards, it is quite unsafe, in the absence of the guidance 
of fossil remains, to attempt any further sub-division of the group. A few of the 
principal features, which were of sufficient importance and distinctness to be mapped, 
have been laid down in the map. The chief of these 1s the occurrence of a band of 
quartzite and silicious slates of no very great thickness which forms a horse-shoe 
bend right across the centre of the Cumbum plain, beginning close to the north end of 
the town and trending north and east and then turning suddenly south and crossing 
the Gundlacumma river just a little above its bend to the north ata distance of 
five miles from Cumbum. South of the river the quartzite beds stretch away south- 
south-east in a nearly straight lime as a generally low ridge, or rather succession of 
ridges, which runs far up the Yamal-air valley and divides it into two parts. 
“This quartzite forms the crest of two large hills in its course; the one the 
elephant hill (the Yanegayconda Trigonometrical Station of the map) two miles north- 
east of Cumbum, and the Mullapoor hill at the mouth of the Yamal-air valley. 
South of the town the quartzite has disappeared and apparently passed into a 
silicious slate, for no quartzite outerop is seen in the bay formed by the Cumbum 
slates south-west of the town. 
“In many parts of the ridge, the band of quartzite is fairly replaced by silicious 
slate; and where this is the case, it is not always possible to state which part is the 
exact representative of the thin quartzite band of a distant part of the ridge. In 
( 236 ) 
