70 SECTIONAL ADDRESSES. 



that of an extensive series of American oil-well records 85 per cent, of the 

 wells sunk in accordance with geological advice proved successful, whereas 

 of those sunk at random only 5 per cent, were productive. In his 

 Presidential Address to this Section at the Bournemouth meeting in 1919, 

 Dr. J. W. Evans, C.B.E., says : — ' The sum total of the funds which have 

 been uselessly expended in this country alone in hopeless explorations for 

 minerals, in complete disregard of the most obvious geological evidence, 

 would have been sufficient to defray many times over the cost of a com- 

 plete scientific underground survey.' 



One of many examples of useless boring for water, coal and oil, that 

 have come under my own notice may be given. In this case boring for oil 

 with a percussion drill was continued for several thousand feet in igneous 

 and metamorphic rocks, imderlying petroliferous sediments. My examina- 

 tion of the core of the bore showed that material thought to be sandy 

 micaceous clay of the petroliferous series, of marine Kainozoic age, was 

 really comminuted biotite-schist, of a much older division of rocks, barren 

 of oil. Had the core material been submitted to a geologist from time to 

 time during the progress of boring its nature would have been recognised 

 at once, and the expenditure of several thousand pounds sterling, as well as 

 a great deal of time and labour, would have been saved. In this case the 

 Kainozoic rocks were fossiliferous, but their lowermost portion consisted 

 of material derived from rocks similar to those of the underlying meta- 

 morphics, a fact that might be advanced as sufficient to excuse the mistake 

 made by the technical men in charge of boring operations. But, since a 

 great thickness of fossiliferous rocks had been bored through and then 

 material found not only showing no fossils, but possessing sufiicient 

 evidence to distinguish it from the sediments that had been bored 

 previously, this mistake should not have been made. 



The Directors of the Geological Surveys of several Colonies have 

 informed me that many thousands of pounds have been spent fruitlessly 

 in boring at unsuitable places in the attempt to get good supplies of 

 underground water. 



These failures were not due to incompetent technical management of 

 boring operations, but to a lack of geological knowledge of rock structure, 

 of the nature of the sediments and rocks bored, the significance of fossils, 

 and the correct interpretation of the evidence from the material obtained. 

 Under existing conditions regarding the qualifications of boring engineers 

 there are limitations to the value of their technical knowledge, unassisted 

 by geological training or timely advice. 



Some bedded rocks, as shale, mudstone and clay, when inclined and 

 saturated, or nearly so, with water, and under great superincumbent 

 pressure, are unstable, and often give much trouble in various engineering 

 works, such as dams, and railway and canal cuttings, as for instance the 

 Culebra cut, Panama Canal. There are many examples of railway- and 

 road-cuttings in which there has been so much sliding of beds that the 

 ground on the inslope side has had to be cut back in numerous benches, 

 some for upwards of 100 yards. Geological advice, if obtained before 

 operations had far advanced, would certainly, in some instances, have 

 shown a means of averting trouble by preventing the saturation of unstable 

 beds. 



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