636 



SCIENCE. 



[N. S. Vol. XVI. No. 407. 



none of them have as yet, to my thinking, 

 been traced to an issue ; and to show the direc- 

 tion in which I hope myself to contribute. 

 C. Barus. 

 Beown University, 

 Providence, R. I. 



CUBRENT NOTES ON PHJSIOQRAPHY. 



RIVERS OF SOUTHERN INDIANA. 



Certain recent essays that might be gathered 

 under the general title, ' Studies of River 

 Development,' are of interest beyond that 

 which concerns the locality that they treat, 

 inasmuch as they illustrate the degree to 

 which one of the most important divisions of 

 physiographic theory finds practical applica- 

 tion. 



The ' Drainage of Southern Indiana,' largely 

 outside of the glaciated area, is explained by 

 Newsom {Jour. Oeol., Vol. X., 1902, pp. 166- 

 180, map) as ' such as would be logically devel- 

 oped in a country of such combination of hard 

 and soft southwestward dipping strata ' as 

 are here found; that is, there are two north- 

 south cuestas formed by the Niagara lime- 

 stone and the Knobstone standstone, with re- 

 spect to which the streams are rather system- 

 atically arranged, in what seem to be conse- 

 quent, subsequent and obsequent courses. The 

 author implies an improbably close agreement 

 between the original extent and the present 

 outcrops of certain formations in suggesting 

 that a certain stream, which follows a longi- 

 tudinal course on weak strata, was deflected 

 into such a course by the sandstones of the 

 next west-lying cuesta when the ' region was 

 first elevated.' The explanation offered for 

 the behavior of one of the master consequents 

 (East White river) in gathering a number of 

 branches from the back (western) slope of the 

 low Niagara cuesta and leading them westward 

 through a notch in the next following Knob- 

 stone cuesta, would have been- strengthened if 

 it had been presented as exemplifying a type- 

 pattern of drainage well known elsewhere. 

 Indeed, inasmuch as this essay is addressed to 

 professional readers, the essential features of 

 the streams might have been more tersely pre- 

 sented in several instances, had they been 

 named in accordance with a consistent termi- 



nology and thus shown to belong to well-recog- 

 nized classes, rather than described in para- 

 phrases as if they had no relatives elsewhere. 

 The close approach of the Ohio to one of the 

 headwaters of East White river seems to indi- 

 cate a great and relatively recent increase in 

 the volume of the Ohio, such as has been in- 

 ferred from other evidence elsewhere. 



RIVERS OF SOUTH WALES. 



The most notable characteristic of Stra- 

 han's ' Origin of the River-system of South 

 Wales' {Quart. Journ. Geol. Soc, LVIIL, 

 1902, 207-225, map) is the neglect of the cap- 

 ture of headwaters of initial consequent 

 streams by the growth of associated subse- 

 quent streams along belts of weak strata. It 

 is shown on good evidence that many streams 

 in the Paleozoic area of South Wales pay no 

 attention to the strong east-west folding or 

 to the pronounced north-northwest faulting 

 of the region; and it is reasonably inferred 

 that they were superposed on the previously 

 much denuded Paleozoic area through a cover 

 of Chalk; but in certain localities where the 

 streams follow a northeast-southwest system 

 of disturbances, a late date is given to the 

 disturbances and the streams are made local- 

 ly consequent upon them. It is recognized 

 that since superposition there has been great 

 denudation, whereby strong relief has been 

 developed appropriate to the resistance of 

 the rocks; but no accompanying adjustment 

 of streams to structures (except in an alto- 

 gether minor case) is considered, although it 

 is rather clear that a number of captures must 

 have taken place, as in the growth of the TJsk 

 headwaters on the Old Red sandstones north 

 of a resistant Carboniferous escarpment and 

 in the associated beheading of several streams 

 south of the Usk. The theory of the adjust- 

 ment of streams to structures is altogether too 

 well demonstrated to be set aside as ' trans- 

 gressing the limits of legitimate speculation.' 

 Yet in accordance with the tacit postulate 

 that all rivers are of consequent origin, Stra- 

 han reverts to Ramsay's theory of an anti- 

 cline to form the divide between the Thames 

 and the Severn. Much of the evidence against 

 this obsolescent solution of the Thames-Severn 



