NATURAL' SCIENCE NEWS. 



The Petrified Trees of Arizona. 



At ft recent meeting of the New 

 York Academy of Sciences a paper on 

 Sume Features of the Arizona Plat- 

 eau was read by L. S. GriBwold. 



In general the plateau surface is 

 between 0,000 and 7.IWI0 feet in elo 

 vnlion above sea level and strikes one 

 as being remarkably smooth for so 

 high elevation; there are large 

 stretches of nearly level or gently 

 rolling country, il iter si tied, however, 

 by mesas aud outliers, with escarp- 

 ments rising between 50 nod 2011 

 feet, shallow but broad old streiin 

 channels now little used and leading 

 to canons with percipitous walls. 

 On the plateau top are numerous vol 

 cauic elevations, varying in age from 

 tht; young cinder cone to tins denud- 

 ed stock. Over the d strict silicified 

 wood is well known, occurring at the 

 base of o gravel and sand horizon, 

 little consolidated, belonging to the 

 late Tertiary or Pleistocene times, 

 and lying with slight unconformity 

 in part upon probable Triassic strata 

 and in part upon Carboniferous, the 

 older formations being little dis- 

 turbed. 



The trees now petrified originally 

 grew to large size, eight or nine ket 

 in diameter for the largest probably 

 conifers, and perhaps not very differ- 

 ent from the forest growth of part of 

 the present plateau. This ancient 

 forest was apparently thrown down 

 by the wind, for tree butts are com- 

 mon in horizontal position while only 

 one was found erect. The gravel 

 and sand covering would seem to 

 have come soon, for only a few have 

 tilling! of sediment in hollows or give 

 other indications of decay; the logs 

 were buried at least fifty or sixty feet 

 deep. The weight of the overlying 

 sediments crushed the trees so that 

 the horizontal diameters are common- 

 ly greater than the vertical as they 

 are seen in place. Silicification was 

 probably accomplished by percolat- 

 ing surface waters, as the logs aie 

 distant from volcanic vents, as far as 

 known to the writer; then no hot 

 water deposits were seen accompany- 

 ing the lo^s, and the distribution as 

 seen over many miles and reported 

 much more widely would alsoi 

 tate a»ainst the theory of change by 

 hot water. — .Scientific American. 



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The Ruined Gila Cities. 



The attention of people interested 

 in archieology and ethnology gen- 

 erally has long beeu directed to 

 the ruins of the cliff dwellings in 

 northern Arizona and southern Colo- 



NATURAL SCIENCE NEWS. 



ado, but there are comparatively few 

 persons outside of Arizona and New 

 Mexico who know that in southern 

 Arizona there is a field fur more in- 

 teresting and of wider range. So 

 eminent authority as Major J. W. 

 Powell, recently of the United States 

 Geological Survey, is quoted in sup- 

 port of this statement. Conservative 

 estimates put the population of the 

 Gila country at fully 1^.000,000 when 

 was at its height. 



The Gila remains have been but 

 little explored because of the inac- 

 cessibility of the region, the intoler- 

 able dry beat during two-thirds of 

 each year, and the total lack of water 

 where it is needed. The mining 

 prospectors who have tramped for 

 years over all the mountains and 

 through every valley in the Territory 

 have Riven no heed to this part of 

 the Gila country, because, no water 

 being there, it would be useless to 

 attempt to develop u mine even on 

 good surface indications. An ex- 

 pedition under Frank Cushiug did 

 some work near Los Muertos, which 

 is known in the Southwest as thePom- 

 peii of Arizona, but with the break- 

 ing down of his health the enterprise 

 came to an end. The area of the 

 country in which the remains of a 

 prehistoric people are found is some 

 300 square miles. It extends from 

 the junction of the Gila and Colorado 

 Rivers eastward to the Superstition 

 Mountains, and from Phoenix on the 

 north almost to the Mexican line. 

 Near Casa Gande the most extensive 

 Indian remains are to be found. 



The country is a ruin from one 

 end to the other. All parts of it bear 

 unmistakable evidences of irrigation 

 codoIb several hundred mileB long 

 and built w-th exactness and skill, 

 and of cities of 30,000 and 40,000 

 population. One can walk for miles 

 and find every foot of the sandy sur- 

 face more or less mixed with broken 

 pottery. The paint is still on them, 

 and is not in the least faded though 

 it has lain exposed for ages. In the 

 locality of Mesa City and Tempe an 

 overflow from the Gila at some dis- 

 tant period washed against the ruins 

 until they crumbled and were spread 

 out level with the country. Back ten 

 miles from the Gila JEiver the ground 

 is higher, and was once the sito of a 

 city. Portions of the wall by which 

 it was protected are still standing 

 more thai twenty feet in thickness. 

 Inside are the mound like ruins of 

 the bouses, which, being leas durable, 

 have crumbled. The buildings must 

 have been very large, for in some in- 

 stances the mounds are 300 feet in 

 length by 200 in width and 20 iu 

 height. The space enclosed by the 

 wall is about fifty miles by three. 



(To be continued.) 



