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SCIENCE 



[N. S. Vol. XXXVII. No. 958 



the Gulf of Mexico on the north and the high 

 volcanic plateau of Guatemala on the west and 

 south. It is to-day one of the worst possible 

 environments for man. In the first place, it re- 

 ceives so much rain that it is covered for the most 

 part with a dense tropical forest or jungle where 

 the excessive moisture and rank growth of vege- 

 tation render it practically impossible to make 

 clearings and practise anything but the most hap- 

 hazard agriculture. In the second place the region 

 suffers to a maximum degree from the disadvan- 

 tages of a uniformly warm, moist, debilitating 

 climate. And finally it is afflicted with the worst 

 kind of tropical fevers which weaken and destroy 

 white men and natives alike and render thousands 

 of square miles practically uninhabited. 



To-day Peten stands at the lowest point in the 

 scale of American civilization. Close beside it the 

 Guatemalan plateau with its drier, less debilitating 

 climate, less dense vegetation, and relative absence 

 of malarial fevers, is far in advance of it, al- 

 though inhabited by practically the same race and 

 governed by the same laws. Formerly the reverse 

 was true; the plateau was, relatively speaking, 

 only moderately advanced; that is, it was a pro- 

 vincial region, while the lowland was for many 

 centuries the seat of a culture equal to that of 

 the highest races of the eastern hemisphere before 

 the days of Greece. In the last 1,500 years, more 

 or less, there has evidently taken place a change 

 of great magnitude. In explanation of this change 

 three possibilities present themselves. First, the 

 Mayas may have possessed a degree of energy and 

 initiative and of resistance to fevers and to the 

 debilitating influence of the torrid zone much in 

 excess of that of any other known people. Second, 

 in their day tropical fevers of the more destructive 

 types may have been unknown in Central America; 

 and, third, the climate may have changed. All 

 three theories are probably true in part, but there 

 is no independent evidence as to the first two. 

 On the other hand, alluvial terraces and their rela- 

 tion to such ruins as Copan furnish strong in- 

 dependent evidence of climatic pulsations during 

 the past 2,000 years. We are therefore led to con- 

 clude that although the Mayas were a remarkable 

 people they did not of necessity excel all other 

 races in their resistance to disease and in their 

 power of overcoming the obstacles of a habitat — 

 lowland forests in the moister portions of the 

 torrid zone. In their day, apparently, the earth's 

 climatic zones were shifted somewhat equator- 

 ward, so that in winter the conditions of the dry 

 subtropical zone of high pressure and perhaps the 



rainless fringes of our cyclonic storms prevailed 

 in the country. The yearly dry season thus pro- 

 duced, probably prevented the growth of dense 

 forests, made agriculture possible, greatly reduced 

 the amount of disease and acted as a direct stim- 

 ulant by relieving the deadening monotony of the 

 almost unchanging moist heat. A relatively slight 

 climatic change such as this would alter the phys- 

 ical environment of Peten from exceedingly un- 

 favorable to relatively favorable, and would ren- 

 der the location of the highest native American 

 civilization rational instead of almost inexplicable. 

 Further Considerations on the Origin of the Him- 

 alaya Mountains and the Plateau of Tiiet: 

 T. J. J. See, A.M., Ph.D. 

 Dana's Contribution to Darwin's Theory of Coral 

 Beefs: William Mokris Davis, Sc.D., Ph.D. 

 It is fitting on the hundredth anniversary of 

 Dana's birth to call attention to a significant con- 

 tribution that he made many years ago to Dar- 

 win's theory of coral reefs, all the more because, 

 although it has high confirmatory value, it has 

 been strangely overlooked by most students of the 

 coral island problem. Darwin, as is well known, 

 explained barrier reefs by an upgrowth of the 

 corals of fringing reefs during a slow subsidence 

 of the central island on which they were estab- 

 lished; but he did not offer any direct confirma- 

 tory evidence of the truth of his fundamental as- 

 sumption of subsidence. Dana furnished inde- 

 pendent confirmatory evidence of the assumption 

 by pointing out that the central islands of barrier 

 reefs are, as far as he had descriptions of them, 

 characterized by embayed coast lines, precisely 

 such as must result if they had subsided; all of 

 their valleys are invaded by the sea and converted 

 into bays. Darwin had noted this fact, but had 

 not perceived its significance, probably because he 

 did not understand that the embayments of a coast 

 line are in nearly all cases formed by the sub- 

 mergence or drowning of preexistent valleys. 

 Dana was the first observer in the world to bring 

 forward this explanation, to-day everywhere ac- 

 cepted, and the first also to apply it to the central 

 islands of barrier reefs. In recent years several 

 Australasian observers have resurrected Dana's 

 idea, and have found in it, as he did, a strong 

 confirmation of Darwin's original theory. 

 Fhe Formation of Coal Beds: John J. Steven- 

 son, A.M., LL.D. 

 Cambrian Fossils from British Columbia (illus- 

 trated) : Charles D. Walcott, Ph.D., Sc.D., 

 LL.D. 

 Dr. Walcott gave illustrations of a very remark- 



