692 ANNUAL EEPORT SMITHSONIAISr INSTITUTION, 192 8 



tion of the morainic material from which the clay is washed out, and 

 other circumstances. By parallel measurements in different local- 

 ities, many such deviations from the true solar curve will probably 

 be eliminated, but meanwhile it is not advisable to transcribe the 

 thickness of the varves into figures intended for exact calculations. 

 Already, however, a really convincing graphic correspondence makes 

 it possible for the first time to introduce the time factor into a great 

 number of geophysical investigations which were hitherto beyond 

 our reach. Thus, to mention a few examples, the possibility of map- 

 ping and dating synchronous land-ice borders over great areas in 

 different regions of the earth renders it possible, in connection with 

 the physics of land ice, to make a rational study of the movement 

 and extension of ice, and of its recession as a function of melting as 

 well as of fracturing. In the papers quoted some hints are given 

 concerning the use of time determination for a closer geophysical 

 study of other processes, such as the evolution of climate, and the 

 erosion along rivers as well as along the shores of lakes and seas. 

 Special mention is made of the magnificent example of the Niagara 

 Canyon, the age of which has now been geochronologically dated by 

 means of good varve connections. Thanks to the excellent measure- 

 ments of American and Canadian geologists we have here a first-class 

 example of the amount of river erosion under certain conditions dur- 

 ing a determined space of time. There is only room here to mention 

 fresh possibilities of studying the way in which the recession of 

 the ice was followed by the formation of soil and vegetable mold, 

 and the immigration of flora and fauna into the former great ice 

 deserts. 



ARCHEO-CHRONOLOGY 



In the autumn of 1024: I had the welcome opportunity of starting, 

 under the auspices of the university," a geochronological institute for 

 the preservation, elaboration, and extension of material in connection 

 with the Swedish time scale and its international use. Up to the 

 present time 12 preliminary papers have been issued from the insti- 

 tute and published in various Swedish scientific journals under the 

 common title of Data. The first of these, Data I, was published in 

 Swedish and was entitled " Forhistoriska tidsbestamningar," or pre- 

 historic datings. It may be well to summarize here some of the views 

 expressed as exemplifying the archeological use of the new time scale. 



The period of man is a late conception in the history of the earth, 

 for the first reliable traces of beings who can be considered deserving 

 of the name of man can hardly be found in deposits earlier than the 

 Quaternary period. These deposits form the comparatively thin 

 soil which covers the older formations with their remarkable re- 



» Of Stockholm. 



