794 



SCIENCE. 



[N. S. Vol. XIV. No. 360v 



SECTION E, GEOLOGY AND GEOGRAPHY. 



Abstracts of papers read before the Sec- 

 tion on August 26-29, 1901, are as follows : 



' Some Problems of the Dakota Artesian 

 System ' : James E. Todd. 



This paper presents some of the unsolved 

 problems found in several years' study of 

 the artesian wells of South Dakota. The 

 artesian system shows four or five aquifers, 

 or water-bearing strata, more or less com- 

 pletely separated from one another. Our 

 first problem is, how is this separation ac- 

 complished ? By sheets of clay wholly, or 

 in part by mutual precipitates between two 

 kinds of water? Again, artesian waters 

 may be divided into soft and hard, and both 

 kinds are found in the same aquifer in dif- 

 ferent localities. This presents the question , 

 what decides the n^ineral content of the 

 water at any place ? Is it what is brought 

 from its original source, or the com- 

 position of the rock in which it is found ? 

 The latter seems most accordant with the 

 facts. Again, though from the hydraulic 

 gradient the flow seems to be uniformly 

 towards the southeast, the soft waters in 

 each aquifer are found toward the northwest, 

 and the hard to the southeast. Therefore, 

 another problem is, how can we explain the 

 lime and less soluble salts replacing the 

 soda and more soluble salts in the same 

 stream? Again, a prominent content of 

 the water about Pierre, and extending west- 

 ward indefinitely, is natural gas, and this 

 gas has been identified with the water itself 

 and not with any carbonaceous stratum 

 above. What then is the origin of the gas ? 

 The high temperature with which it is asso- 

 ciated, 92° to 102° F., and its intimate 

 mixture with the water, suggest a chemical 

 origin, but nothing in that line, which has 

 been hinted by any chemist, can be con- 

 ceived to occur in this region. There is no 

 trace of volcanic or crustal disturbance, but 

 from geological relations there is strong 

 ground for believing that extensive carbon- 



aceous deposits may have been formed in 

 the Carboniferous period a little west of 

 Pierre, the eastern edge of which the Dakota 

 formation, which bears the water, directly 

 overlaps. Subterranean heat may distill 

 the gas into the overlying water stratum, 

 carrying thehighertemperature from below, 

 and perhaps adding to it by condensation. 

 But, perhaps more strange, a few miles east 

 of Pierre the gas disappears and the tem- 

 perature of the water declines 20 degrees 

 or more. We have, therefore, another very 

 obscure and difficult problem. What be- 

 comes of the gas ? This problem in some 

 respects resembles the disappearance of 

 soda ingredients in the water, mentioned 

 above. Perhaps the readiest suggestion is 

 that the gas escapes from the water to the 

 surface, by its greater penetrating power, 

 but no gas springs have been.found, and 

 only a little at higher levels, which has 

 been discovered in shallow wells. We have 

 already alluded to the phenomenally high 

 temperature of some wells. This has been 

 well discussed by Darton in the 18th Annual 

 Report U.S. G. S. The oxidation of pyrites 

 he considers inadequate, yet as the higher 

 temperatures are connected with the pres" 

 ence of sodium chloride and gas, so far as 

 we know, it is strongly impressed upon us 

 that some chemical reactions yet undis- 

 covered have something to do with the 

 high temperature, origin of gas, and disap- 

 pearance of sodium salts in the great east- 

 ward-flowing streams of artesian waters. 



* Interpretation of Some Drainage 

 Changes in Southeastern Ohio ' : W. G. 

 Tight. 



This paper traces some old river valleys 

 and indicates the sequence of events during 

 the changes and the time of the inaugura- 

 tion of the changes. 



' Moraines and Maximum Diurnal Tem- 

 perature ' : James E. Todd. 



It has been noted that the moraines in 

 the James River valley are frequently 



