124 Dr. H. Preiswerk—Oul Region of the Northern Punjab. 
VII. Summary. 
The following features are favourable to contemporaneous age :— 
1. Spherical form. 
2. Sporadic distribution or occurrence at a pause in 
sedimentation. 
3. Gravitational bedding around the nodule. 
4. Modern occurrence. 
The following features are favourable to the subsequent relative 
age -— 
1. Replacement of the fossils, grain, and structural features of 
the parent rock. 
2. Displacement of the stratification lines, above and below the 
nodule, conformably to its shape. 
3. The development of a vertically flattened form. 
4. The arrangement of the nodules in lines showing a marked 
rhythm. 
It should be hardly necessary to remark that no one of these 
features can be decisive. The whole of available evidence must be 
taken into account, and considered with any special local evidence 
that may be available. Thus, G.W.Lamplugh’s? observation that 
a band of crushed ammonites passes through the nodules puts the 
date of the concretion as later than the crushing. The subject is 
difficult and agreement is far from being reached, although the 
matter has received the attention of generations of able geologists. 
I should like to express my thanks to Professor H. H. 
Swinnerton, D.Sc., and to Messrs H. 8S. Holden, M.Sc., and H. C. 
Sargent, F.G.S., for discussing various aspects of this work with me. 
On the Geological Features of the Oil Region in the 
Northern Punjab (British India). 
By H. Preiswerk, Basle. 
(Concluded from p. 80.) 
Occurrence of the Oil—The oilfield of Jaba and those of Rawalpindi 
and Fatehjang are identical from the stratigraphical point of view. 
At Jaba, too, the oil is to be found in the contact zone between 
the Nummulitic limestone and the younger gypsiferous clays of 
the Upper Nummulitic. These gypsiferous clays represent a bed 
well adapted to favour the accumulation of oil, wherever they cover 
the limestone at a moderate inclination. The oil issues only from the 
limestone, but the cellular limestone, too, may be oil-bearing in 
depth. It may be pointed out that cellular limestones of the same 
character accompany the oil-shows at Gunda, the main oil-spring 
in the neighbourhood of Fatehjang. 
At Chota Kutta and Burra Kutta the oil flows out mixed with 
1 Lamplugh, Quart. Journ. Geol. Soc., vol. xiv, 1889, p. 582. 
