GEOLOGIC WORK OF ANTS IN TROPICAL AMERICA. 1 



[With 1 plate.] 



By J. C. Branner. 



INTRODUCTORY. 



In 1900 I published a short paper on the geologic work of ants in the 

 Tropics. 2 Since then a good many additional observations, notes, and 

 photographs have been made, and the most important of them are 

 here brought together in a single article. 



There are many brief notes on the work of antg scattered through 

 the writings of travelers in tropical countries, but these notes are for 

 the most part repetitions of rather vague and sensational stories 

 which make no claim to accuracy of statement, so that they would add 

 little or nothing to the value of the article. No attempt has there- 

 fore been made to use such notes except in so far as they seem to 

 afford new or important corroborative evidence. At the same time 

 it is realized that some of the things that ants do in tropical countries 

 are so remarkable that those who have no personal experience of 

 them may be pardoned for regarding the stories told about them with a 

 certain amount of suspicion. For this reason I have confined myself 

 to my own observations and to some of our most trustworthy scientific 

 writers, such as Bates, Belt, and Spruce, who are naturalists to be 

 taken seriously. 



The best anyone can do who has not seen the work of ants in trop- 

 ical countries is to turn to what can be seen in temperate regions. 

 But the work done by ants in temperate zones is, with a few excep- 

 tions, of no geologic importance at all as compared with that done 

 by them in some parts of the Tropics. 



The work of the ants, in so far as it is of geologic importance, con- 

 sists chiefly of their nests, habitations, refuse heaps, or mounds, above 

 ground and their burrows, tunnels, passageways, and other excava- 

 tions beneath the surface, and the opening up of the soil and the 

 subjacent rocks to the various atmospheric influences. 



1 Bead before the Cordilleran Section of the Geological Society of America Mar. 25, 1910. Manuscript 

 received by secretary of the society Apr. 29, 1910. Published Aug. 20, 1910. Reprinted by permission 

 (condensed by author) from Bulletin of the Geo ogical Society of America, vol. 21, pp. 449—196. 



* Journal of Geology, vol. S, pp. 151-153. Chicago, 1900. 



S03 



