90 Bulletin American Museum of Natural History. [Vol. XXXVI, 



must also take into consideration the subsequent modifying factors of 

 glaciation, subsidence and erosion. 



In 'Die Kordillere von Bogota' Dr. Alfred Hettner^ gives the results 

 of his studies of glaciation in the Eastern Andes showing that at their maxi- 

 mum development glaciers which are now retreating were, in at least one 

 instance, 460 meters lower than at the time his observations were made. 

 He writes (p. 74): 



" During the last years and decades the boundaries of the snow and the 

 glaciers have probably retreated to a large extent. All the people who 

 served me as guides here agreed to the same opinion; and that the retreat 

 must have been quite marked, may be gathered from the words of a peddling 

 Indian tradesman, who expressed his lively ill-will for the visits of strangers 

 in the mountains, for he thought they were to blame for the disappearance 

 of snow. Upon the snow-covered mountain of San Paulin, the smooth 

 nature of the strata on the western side for several hundred meters below 

 the present snow line clearly shows that it was until recently covered with 

 snow. We have previously heard that from the foot of the Sugar-loaf 

 Glacier to a distance of 700 to 800 m. and a difference in height of 80 m., 

 a great amount of end moraines are found, upon which no plant growth has 

 yet been able to settle, which must, therefore, be of a very recent origin. 

 About contemporaneous with the retreat of the snow-line of the Alps and 

 that of many mountains, the snow-line of the Colombian Andes also re- 

 treated." 



On the succeeding page (75) he adds: 



"In more ancient times the glaciers must have been much larger, the 

 climate consequently cooler, for I noticed on the slope of the valley, to a 

 distance of at least four or five km. from the present foot of the glacier, 

 about 460 m. lower, a row of plain end moraines grown over, and it is possible 

 that they extend down further. 



"Even if the observation that is taken in general delineations and in 

 text-books does not possess any proof, the fact of the existence of an ice 

 age in the Andes of Colombia, and supposedly also of Venezuela, may be 

 considered as certain. Regarding the appearance of two ice ages, no 

 intelligence has yet been gathered from the equatorial Andes up to the 

 present time." 



It seems evident, therefore, in view of the different climatic conditions 

 which must have prevailed in the Andes during the period of maximum 

 glaciation, that the existing zonal boundaries are post-glacial. Without 



1 Petermaim*s Mittheilungea Erganzungsband 22. pp. 74, 75. I have to thank Dr. Chester A. 

 Heeds for these references and the accompanying translation. 



