The eastern Andes of central Bolivia were crossed by the authors in December, 1919, during the progress of geological exploration for Richmond Levering and Company, whose courtesy makes this paper available. The observations made during the traverse, 200 miles long and 10 days in duration, between Cochabamba, on the west, and Santa Cruz, on the east, were rendered more comprehensive and understandable by subsequent work north and south of Santa Cruz, along the east front of the mountains.
Our exploratory expedition left Cochabamba on December 3 and proceeded by train to Arani, the terminus of a short narrow-gauge railway, which now (October, 1921) is being extended farther eastward toward Totora. From Arani we traveled by mule train across the successive ranges of the Cordillera Oriental past Totora, Chilon, Pampa Grande, and Samaipata to Santa Cruz, which was reached the evening of December 13 (see figure 1). The necessities of . . .