460 j. c. branner geologic work of ants 



Introductory 



1 



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

 tropics.^ 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 ants 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, therefore, been made to use 

 such notes except in so far as they seem to afford new or important cor- 

 roborative 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 quoted directly, and sometimes at considerable length, from 

 some of our most trustworthy scientific writers, especially from Bates, 

 Belt, and Spruce, all of whom are naturalists to be taken seriously. 



The best any one can do who has not seen the work of ants in tropical 

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

 should be insisted on that the work done by ants in temperate zones is, 

 with a few exceptions, 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, consists 

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

 and their burrows, tunnels, passageways, and other excavations beneath 

 the surface, and the opening up of the soil and the subjacent rocks to the 

 various atmospheric influences. 



In the United States we have very little evidence of ants making either 

 underground passageways or mounds of sufiicient size or extent to have 

 attracted much attention. Indeed, it seems to be generally conceded by 

 entomologists that the ants of the northern part of North America are 

 not as enterprising as those farther south, or even as those of Europe. 

 Forel seems to have found the structures of our North American ants so 

 insignificant that he avoided speaking of them as having mounds at all. 

 Certainly the little ant-hills we have seen in most parts of the United 

 States are too insignificant to attract the attention of geologists. In the 

 South and Southwest they are somewhat more conspicuous, and in the 

 semi-arid portions of western Texas and in Arizona, New Mexico, and 

 parts of California they have attracted not a little attention. 



« Journal of Geology, vol. vlll, pp. 151-153. Chicago, 1900. 



