82 PROCEEDINGS OF THE PRIXCETOX MEETING 



The Jurassic and Pennsylvania rocks of the southern Colorado section are 

 white or gray in prevalent colors. Red is mainly confined to the Triassic and 

 Permian beds. In view of these and other well known variations in the dis- 

 tribution of a notable reddish color in Paleozoic and Mesozoic beds of the 

 Rocky Mountain region, it seems undesirable to continue the use of the term 

 "Red Beds" for the sediments of a particular region. It has not the value in 

 correlation once assumed for it. 



Prof. D. W. Johnson : From the Cerrillos region, New Mexico, I have de- 

 scribed two series of Red Beds of a similar appearance only a few miles apart, 

 one of Upper Cretaceous or Laramie age, the other belonging to the group de- 

 scribed by Mr. Darton. Some bitter discussions were waged by the earlier 

 workers in this region as to the stratigraphic position of "the Red Beds" near 

 Cerrillos, the disputants not recognizing that they had observed distinct forma- 

 tions. This emphasizes the need, just pointed out by Doctor Cross, of qualify- 

 ing the term "Red Beds" in such manner as to avoid confusion. 



Presented in full without notes. The paper was briefly discussed fur- 

 ther by Prof. E. D. Salisbury. 



SOLAR HYPOTHESIS OF CLIMATIC CHANGES 

 BY ELLSWORTH HUNTINGTON 



i Abstract) 



At the last meeting of the Society the writer presented an hypothesis of 

 the possible relation of solar activity to various terrestrial phenomena. Fur- 

 ther study has convinced him that the hypothesis should be divided into two 

 distinct parts whose degree of probability is widely different. The facts pre- 

 sented as to earthquakes may perhaps indicate some relationship between 

 such phenomena and changes in the sun, but any such relationship is evidently 

 highly complicated, and the data now at hand scarcely suffice to warrant a 

 working hypothesis along these lines. On the other hand, further investiga- 

 tion of the relation of the sun to terrestrial climate brings out some striking 

 agreements. 



In all scientific work the normal process is to determine the causes of pres- 

 ent phenomena and then to ascertain whether past phenomena of a similar 

 nature may have been due to similar causes working on a different scale. In 

 the study of geological climates the apparent gap between the great changes 

 of geological times and the minor variations which are now in progress has 

 greatly restricted this method of study. Measurements of the rate of growth 

 of trees in California during the past 3,000 years, however, together with 

 other lines of research, seem to show that the supposed gap between the minor 

 changes of the present and the great changes of the past is bridged by inter- 

 mediate phenomena of almost every grade. Therefore there seems to be 

 strong reason for applying the normal scientific method of investigating the 

 causes of present climatic changes and then determining how far the same 

 causes may apply to the past. 



The chief objections to the solar hypothesis have been (1) its indefiniteness, 

 (2) the supposed inadequacy of observed solar changes to produce any appre- 

 ciable meteorological phenomen^a, (3) the lack of any direct evidence that the 



