THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Aet. YIII. — Geologic Reconnaissance of the Ayusbamba 

 {Peru) Fossil Beds / by Herbert E. Gregory.* i 



Introduction. 



On the basis of information furnished by Dr. A. A. Giesecke, 

 President of the University of Cuzco, a preliminary excursion 

 to the hacienda of Ayusbamba, province of Parnro, was made 

 by Dr. George F. Eaton in October, 1912. The object of 

 this visit was to investigate the reported discovery of fossil 

 vertebrate remains. The region appeared to Dr. Eaton of 

 sufficient interest to warrant further field work, and accord- 

 ingly, under instructions from the Director of the Peruvian 

 expedition, arrangements were made for a week's study of the 

 Ayusbamba area. The party which left Cuzco on November 

 13, 1912, equipped for geologic and topographic work, and for 

 making collections of fossils, consisted of Herbert E. Gregory, 

 geologist ; George F. Eaton, osteologist ; K. C. Pleald and 

 Carlos Duque, topographers ; and Jose Gabriel Cosio, professor 

 of Sociology and History in the University of Cuzco. 



Geography. 



From Cuzco the trail to Ayusbamba enters the valley of the 

 Huancaro, and follows the south branch of that stream to its 

 source in the bogs of the upper plateau, at an elevation of 

 13,500 feet. Passing over the gracefully molded, grass-floored 

 highland which marks the upper extent of the tributaries of 

 the Rio Huatanay, the trail enters the Apurimac watershed. 

 Perched high on mountain flanks, heading canyons, traversing 

 fields of yareta, and zigzagging among glacial bowlders, along 

 spurs and down talus slopes, the path winds its way toward 

 * Geologist, Peruvian Expedition of 1912. 



Am. Jour. Sci. — Fourth Series, Vol. XXXVIT, No. 218.— February, 1914. 

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