WEATHER AND GLACIATION 



By Chester A. Reeds 



INTRODUCTION 



Weather as it afTects p^laciation is a subject Avhich has been under 

 observation during the past century. Remnants of the last glacia- 

 tion still exist in Greenland, Antarctica, and on some of the islands 

 of the polar regions and in tlie high mountain fastnesses of the 

 temperate and tropical zones. Weather conditions are modifying 

 these ice masses; in fact, the variability of the weather causes 

 glaciers to grow at certain times and Avane during other periods. 

 The changes that are going on to-day are apparently similar to 

 those that took place during past ages. 



There is a distinction between weather and climate. Climate is 

 the average of normal conditions of the atmosphere, while weather 

 constitutes the variations from the normal. Weather changes are 

 of a day-to-day occurrence. When averaged for the year and for 

 longer periods, they yield differences which make the weather of 

 one year vary from that of another, as Tvell as for groups of years. 



During the last decade a few meteorologists have correlated 

 weather changes with variations in solar radiation. This correlation 

 has been specially emphasized by H. H. Clayton in his volume. 

 World Weather, 1923. The correlation of changes in glaciation 

 with solar radiation variations has been mentioned b}' various scien- 

 tists, but it has not been discussed in the light of recent develop- 

 ments. In this paper special application of these changes to glacial 

 deposits at Haverstraw, N. Y., and New Haven, Conn., will be made. 



THE CONDITIONINC, OF ICE SHEETS AND GLACIERS 



Tlierc arc two opposing factors which modify ice masses — namely, 

 nourishment and depletion. Nourishment consists primarily of snow- 

 fall, hoar frost, rime, glaze, sleet, and needles, or spiculae, sometimes 

 referred to as " frost snow " or " polar snow." According to Antevs 

 (1929), depletion occurs through melting, evaporation, discharge of 

 bergs, etc. Melting, which is the most important agent, takes place 

 through high temperature, insolation, and to a minor degree from 



' Atlflrcss before section E of the American Association for the Advancement of 

 Science, Dec. 27, 1928. Reprinted by permission from the Bulletin of the Geological 

 Society of Anrerica, vol. 40, pp. 597-630, Dec. .'11, 1920 



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