334 CARNEGIE INSTITUTION OF WASHINGTON. 



product of freezing and involves also the concentration of CO2. The low 

 temperature gives the power to hold about a double portion of dissolved COj. 



Starting with the warm oceanic water — which fossilized marine life im- 

 plies for the greater part of geologic time in the polar as well as other basins — 

 the progressive double charging of the ocean waters with CO2 must have 

 depleted the atmosphere. The process of depletion is assumed to have 

 continued until the first charged water began to come to the surface in low 

 latitudes and give up its supercharge because of high temperature. Mean- 

 while the polar charging is assumed to have grown less effective because of 

 partial exhaustion of the atmospheric supply, which, however, would begin 

 to be measurably restored when the increased output in low latitudes made 

 itself felt. Thus, a cyclic atmospheric effect is assumed to have been super- 

 posed on the filling of the abyssal basins with ice-cold sahne waters as an 

 incident of freezing in the polar basins. 



A paper has been published during the year giving in much detail the 

 assigned method by which the cold sahne abyssal waters are formed, and this 

 carries the basis for a rough estimate of the time required for a single filling 

 of the abyssal basins with their characteristic water. Preliminary results indi- 

 cate that the period is not likely to be less than that of a glacial-interglacial 

 epoch. The cycles of greatest length and of the highest order of importance, 

 geologically, are assigned to the contests for mastery between the two funda- 

 mental systems of deep-sea circulation, the battle between low temperature 

 and salinity for the mastery of the abyssal basins. The evidence of changes of 

 deep-sea dominance rests on the following basis: 



At present the deep-sea basins are unquestionably under the control of 

 polar influence. In these regions waters of rather high salinity and distinctly 

 low temperature are generated and creep slowly into the abyssal basins of 

 low latitudes and there gradually rise and displace lighter waters. In the 

 very arid regions, saline waters are formed by evaporation and descend to 

 depths of 2,000 meters, more or less, contesting the complete dominance of 

 the polar waters. The present struggle for mastery thus lies in the middle 

 and upper horizons of the ocean. The trend of the contest at present is 

 unknown, but there can be no doubt that the polar elements have dominated 

 since the beginning of Pleistocene glaciation. So, too, there is little reason 

 to doubt that during the earlier periods of glaciation of the Pleistocene type, 

 and still less during the periods of glaciation on the borders of the tropical 

 zone, similar ice-cold saline waters filled the abyssal depths and dominated 

 the whole circulation. But, on the other hand, there were still longer periods 

 in which the fossilized marine Hfe seems to indicate that warm seas prevailed 

 in the high latitudes and in all other latitudes, so far as known. This evidence 

 seems to exclude the hypothesis of such icy dominance from lack of the 

 requisite generating areas. It seems a logical conclusion that saline density 

 generated in low latitudes then held the mastery and that the warm dense 

 waters creeping to the polar regions gave them the benefit of a stupendous 

 natural water-heating system. Under this interpretation, the time-factors 

 of such climatic alternations rise to the grade of geologic eras. 



Two papers bearing on this larger and strictly geological phase of the 

 time element in the climatic problem have been published during the year.^ 



^ A venerable climatic fallacy, Jour. Geol., vol. xxxi, pp. 179-191 (April-May 1923). 

 Significant ameliorations of present Arctic climates, Jour. Geol., vol. xxxi, pp. 376-406. 



