508 PROCEEDINGS OF THE ACADEMY OF [Juiie, 



Wilkes- Barre, could be at least 110 feet deeper than the apparently 

 lowest possible outlet of the same valley near Bloomsburg, and 

 ninety feet deeper than the one near Sunbury, as pointed out by 

 Stale Geologist Lesley in the Pennsylvania State Geological Report 

 G 7, 1883, p. XV, and by Assistant Geologist Prof. I. C. White, 

 at p. 26. Later, in the Summary Final Report, Vol. Ill, Pt. I, 

 1895, p. 2019, Assistant Geologist A. D. W. Smith gives a still 

 greater depth recently found in the buried valley, at two miles 

 below Wilkes-Barre, namely, 220 feet below the present Blooms- 

 burg outlet, and 200 feet below the Sunbury one. The complete 

 understanding of the buried valley in question is of the weightiest 

 practical importance to the operators of the Wyoming anthracite 

 basin ; for the driving of coal mines unexpectedly into the glacial 

 rubbish full of water has repeatedly caused loss of life and prop- 

 erty, sometimes on a large scale. The consequent consciousness of 

 danger and uncertainty about its conditions exact great caution ; 

 and, perhaps, the guarding against unknown possibilities may occa- 

 sion great losses that might to some extent be avoided if only the 

 circumstances could be better understood. Several theories have, 

 therefore, been devised in explanation of the observed facts; but 

 none have proved to be at all satisfactory. It has, for example, 

 been suggested that the glacier itself, before retreating and leaving 

 the rubbish, may have scooped out the valley to that depth. But 

 Lesley and others have repeatedly pointed out how insignificant is 

 and must be the erosive action of glaciers; and, furthermore, it 

 appears highly improbable that a glacier could not only scoop out 

 a deep valley, but carry the vast amount of eroded material over 

 the lip of the basin. In this case, too, that lip, near Bloomsburg, 

 is about twenty miles beyond the nearest point ever reached by the 

 glacier. In 1 883, Lesley, in the passage just cited, was momenta- 

 rily persuaded that there was no escape from admitting that the 

 result had been accomplished by " subglacial erosion — rivers beneath 

 the ice sheet, charged with angular drift materials, plowing deep 

 valley-grooves in the softer coal measures." But in the Summary 

 Final Report, Mr. Smith states that Lesley " now regards his 

 theory of subglacial erosion as wholly inadequate." Indeed, it 

 would be hard to conceive how subglacial rivers could have main- 

 tained an erosive current at such a depth below the outlet of the 

 valley. Mr. Smith cites the opinion of "at least one prominent 

 mining engineer," that the buried valley " has no connected 

 channel, but that the deep places are formed by a series of pot 

 holes." It is true, pot holes are a subordinate glacial feature of 

 the buried valley, and extend below its bottom forty feet or more 

 into the coal measures, as described by Ashburner in the State 

 Geological Report for 1S85. But it is hardly conceivable that 

 excavations on so grand a scale, as hundreds of bore holes have 

 shown the buried valley to be, should have been effected, like pot 



