GEOLOGIC WORK OF ANTS BRAN NEE. 



315 



In some places they stand so close that their bases touch each other, 

 though such cases appear to be rather exceptional. The mounds in 

 this part of Minas and Bahia that appear to have reached their full 

 development range from 1 to 4£ meters in height and from 3 to 10 

 meters in diameter at the base. The biggest of these mounds — 

 that is, one 4.5 meters high and 10 meters in diameter — contains 

 approximately 117 cubic meters of earth. 



At one place in the Rio Utinga region, where the forests had been 

 cleared away so that the mounds were clearly visible, I selected a 



"*»-"■ CLS/i^fe*. 



FlG. 2. — Ant hill (Formiga de mandioca) near Mundo Novo, State of Bahia, Brazil. 

 [From a photograph by R. Crandall, 1907.] 



spot where the} 7 were strikingly abundant, and measuring a space 

 100 by 100 meters, as nearly as it could be done by pacing, counted 

 the mounds within the area and estimated their heights and diam- 

 eters at the base. 



The slopes of these mounds vary from less than 30 degrees up to 47 

 degrees, and on some parts of them there are even perpendicular 

 places. It was thought that 38 degrees was a fair average for the 

 ones in this particular area. 



