Til 10 KUKASIA COAI.KIIOr,!). 
196 
A brief discussion of t,h(^ probahlo rolatif)n8liipH of thft outcrops 
is, however, necessary. In the fir.st places 
Aneroid i'('U(liiif,'N. ... i • i • i i 
it i,s important to emphasise the point, already 
made on pajfo 178, that with very rare exceptions the coal crops 
out only in the nal((N or water-(;ourses, beinjj; entirely covered by 
soil, debris, and jiin<i;Ie, on the interveninfi; slopes and spurs. Any 
correlation of outcrops is, therefore, not a matter of certainty, 
but of probability. The dips beinji; as a rule nil or very gentle, 
the aneroid is obviously as important as the hammer in this work, 
and the former instrument was tested to tlie full. My two base 
stations were my cam]) at Chirmiri, fixed as 2,100 feet by compari- 
son with Bartunga Hill ( A 2,917 feet) and my camp at Kurasia, 
fixed as 2,200 feet by comparison with Kurasia Ilill ( A 2,847 
feet). ]3ut although the difference in heiglit between these two 
camps was by these measurements just 100 feet, yet on the two 
occasions when I travelled from one to the other, the difference 
appeared to be greater (230 and 155 feet respectively) ; but in each 
case I attribute these difTerences to unsettled weather, and prefer 
to rely upon the results of direct comparison with the hills men- 
tioned. I have dealt with this point in detail because on the 
relative heights of these two camps depends any attempt at correla- 
tion between the outcrops observed from Chirmiri with those 
examined from Kurasia. On the relative heights, of the outcrops 
observed from one camp alone considerable reliance may be placed, 
because of the careful application I made throughout the day of 
corrections for diurnal variation, using a scale of corrections locally 
determined, and because in each case I returned after the day's 
work to my starting point and was able to distribute any error 
caused by weather changes, which, however, were mostly very 
small whilst I was examining this field. 
A. The Kurasia Area. 
As the Gorghela Nala gives a good section of the field, I will 
discuss the Kurasia area first, confining this term to that portion 
of the field lying east of the ridge on which runs the road from 
Kurasia to Dubchola. In the Gorghela itself I saw only 4 seams 
(including Kundo Pani, the headwater of the Gorghela) ; but taking 
^ into account outcrops seen in tributaries of 
this nala (Nag Jhula, Saruphkha Nala, 
Bansa Dandi, etc.) we may count 5 horizons in all, with perhaps 
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