834- Sir Boverton Redwood [June 7, 



vegetation of this period exhibits a great analogy with the present 

 flora of the temperate regions of the northern hemisphere, and in the 

 seas were new races of molluscs in great quantity. 



Not less important than the provision of adequate supplies of 

 organic matter to be transformed into petroleum is that of a suitable 

 rock-formation for its reception and conservation. For the latter 

 we need a porous stratum, such as coarse-grained sandstone or con- 

 glomerate or dolomitised limestone, with an impervious cover, such 

 as that provided by fine-grained shale. In addition, in order that 

 the wells drilled may furnish individually a large yield of oil, it is 

 essential that the petroliferous strata should have been caused to 

 assume an anticlinal structure. Under these tectonic conditions any 

 natural gas accompanying the oil accumulates at the crest of the 

 anticline, whilst the oil occupies the flanks, and water is found in the 

 synclines. The gas often occurs at a pressure of many hundred 

 pounds on the square inch, and it is obvious that in these circum- 

 stances a well drilled into the flank of the anticline may produce an 

 oil fountain. 



The geographical distribution of petroleum is no less wide than 

 the geological, as will be seen from the next slide, whereon the 

 principal occurrences are marked in red, but the deposits mainly 

 occur along well-defined lines, often associated with the mountain 

 ranges. This is chiefly due to the formation, in the elevatory process, 

 of minor folds, which have arrested and collected the oil in richly- 

 productive belts, between more or less barren areas, in the manner 

 already referred to. 



There are, however, but few of the localities indicated as petrol- 

 iferous which contribute largely to the world's output of petroleum, 

 estimated for last year as approximately 70,403,128 metric tons. 

 This is shown in the following slide. 



The predominant contributor, as will be observed, is the United 

 States, ^\hicli furnished no less than 64*74 per cent of the estimated 

 total for 1017, the others in order of importance being : Russia, Avith 

 1 3 • 2G per cent ; Mexico, with 11-37 per cent ; the Dutch East Indies, 

 with 2*74 yjer cent; Roumania, with 2*08 per cent; India (Burma 

 and Assam), with 1*61 per cent ; Persia, with 1 * 32 per cent ; Galicia, 

 with 0*1)47 per cent ; Japan, with 0*615 per cent ; Peru, with O'oll 

 per cent ; Trinidad, with 0*303 per cent ; Germany, with 0* 180 per 

 cent; the Argentine, with 170 per cent; Egypt, with 0*094 per 

 cent ; Canada, with * 037 per cent ; Italy, with * 002 per cent ; and 

 other countries, with • 006 per cent. 



It is nofc surprising that the flood of oil which has been poured 

 out by the wells of the United States in ever-increasing volume since 

 1859 should now be attended by signs of the approaching exhaustion 

 of the petrolifei-ous territory, and it has been estimated ]\v Dr. 

 David T. Day that, at tlie present rate of increase of the output of 

 petroleum, the known oilfields of that country will, on the basis 



