PUNJAB OIL REGIOjST, 



9 



breaking them apart, and letting them fall, as soon, at least, as the ice that may still 

 unite them melts away. Such loosened masses could only fall down a pretty steep 

 slope. It may be that this action of the frost takes place sometimes, though rarely, 

 in this region ; but it cannot happen often in so hot a climate. 



e. For the same reason, there is no sign whatever of the action of ice or glaciers, 

 with their grooving and polishing of the rocks by the pebbles and mud they push 

 along, and with the heaps of rubbish that they leave behind them melted. 



It is plain from v/hat has been said that, as the topography is so far from being 

 accidental and is so thoroughly modified by the nature and position of the rocks ac- 

 cording to simple laws, its careful study is of the greatest importance in making the 

 geology clear ; even if not quite so indispensable for the general geology of a large 

 region as for the geological details of a small tract. A merely shaded or hachured 

 map shows some of the geological facts along with a part of the topography, but is 

 very indefinite and imperfect and insufiicient for both, as compared with a contour 

 line map. Such work may sometimes seem too laborious and time-taking, but is 

 after all so necessary as to be worth the trouble. 



IV. KOCK G-EOUPS. 



The geology of the region or of large parts of it has been treated of by Dr. W. 

 Jameson (Journal of the Asiatic Society of Bengal, 1843), Dr. A. Fleming (Jour. 

 As. Soc. Beng., 1848 and 1853), Mr. W. Theobald, Jr.^ (J. A. S. B., 1854), Mr. A. M. 

 Verchere (J. A. S. B., 1S66-G7 ; and as far as it relates to the oil has been dis- 

 cussed in my ovfn " General Seport on the Punjab Oil Lands, Lahore, 1870. " Mr. A. 

 B. Wynne, of the Geological- Survey of India, has spent the two last winters in ex- 

 ploring the Salt Range and mapping its geology, but beyond a paper or two on special 

 places in the "Records of the Geological Survey of India, " his observations have not 

 yet been made public. To save the trouble of turning to those works it may be 

 worth while to give here a short sketch of the geology, so far as known, aside from 

 the structure, which has been already described. 



The old alluvial rocks that have been mentioned, as covering much of the table land 

 are of unknown thickness (more than, fifty j^ards at any rate), and perhaps pass up- 

 ward in some places without interruption into the newest alluvium or wash. It is 

 also possible that in places they pass downward without interruption into the rocks 

 that have been called Sivalik. 



We have then this general section of the rocks of the region : 

 [N'ew, little disturbed rocks : Thickness 

 Alluvium, or wash, ------- unknown, 



A. P. S. — VOL. XV. C. 



