556 POPULAR SCIENCE MONTHLY. 



give rise to maximum erosion, and therefore abundant sediments 

 of sandstone and clay, and comparative poverty of life and there- 

 fore of limestone. Chamberlin also gives reasons why the oceanic 

 periods should be warm, humid, equable in temperature, and the 

 atmosphere highly charged with CO2, and therefore highly favor- 

 able to abundant life, both vegetal and animal, while land periods 

 would be drier and cooler, the atmosphere deficient in CO2, and 

 therefore cold from that cause and in many ways unfavorable to 

 abundant life. 



These extremely interesting views, however, must be regarded 

 as still on trial, as a provisional hypothesis to be sifted, confirmed, 

 or rejected, or in any case modified, in the next century. 



Lastly, it is interesting to note the ever-increasing part taken 

 by American geologists in the advance of this science. There has 

 been through the century a gradual movement of what might be 

 called the center of gravity of geological research westward, until 

 now, at its end, the most productive activity is here in America. 

 This is not due to any superiority of American geologists, but to 

 the superiority of their opportunities. Dana has well said that 

 America is the type continent of the world. All geological prob- 

 lems are expressed here Avith a clearness and a simplicity not found 

 elsewhere. We must add to this the comparative recency of geo- 

 logical study in this rich field. In Europe the simpler and broader 

 problems are already worked out, and all that remain are difficult 

 problems requiring much time. In America, on the contrary, not 

 only are all problems expressed in simpler terms, but many great 

 and broad problems are still awaiting solution. For these reasons 

 the greatest activity in research, and the most rapid advance dur- 

 ing the next century, will probably be here in America. 



"SALAMANDERS" AND "SALAMANDER" CATS. 



By NOHMAX ROBINSON. 



IN many places in the extreme Southern States, especially in 

 what is locally known as the " piney woods," one of the most 

 notable features is the constantly recurring mounds of yellow sand 

 which everywhere dot and, it must be confessed, disfigure the 

 monotonous landscape. These piles of earth are usually nearly 

 circular in form, fairly symmetrical in contour, from six inches to 

 two feet in diameter, and, save where they have been beaten down 

 by rain or winds or the trampling of cattle, about half as high as 

 they are broad. Often these sand heaps are pretty evenly dis- 

 tributed, sometimes so thickly as to cover at least one fourth of the 



