778 



SCIENCE. 



[N. S. Vol. XIV. No. 359 . 



ne saws, lying either side of the ovipositor.' 

 Nor, if a cicada is referred to, does the descrip- 

 tion of the method of oviposition accord with 

 the fact. Finally, it might be desirable for Mrs. 

 Williams to get the real facts concerning honey- 

 bees, that the rate of her ' fair intelligence ' in 

 middle Tennessee be not fixed unjustly low. 

 J. B. S. 



CURRENT NOTES ON PHYSIOGRAPHY. 



THE HIGH PLAINS OF COLORADO, KANSAS AND 



TEXAS. 



The attractions of the diversified Cordilleran 

 region have caused the relative neglect by the 

 geologist and the geographer of the more mo- 

 notonous area of the Great plains during the last 

 thirty years of exploration. Following the re- 

 cent increase of attention to this extensive 

 area, we now have an admirably lucid report 

 on 'The High Plains and their Utilization,' by 

 W. D. Johnson (2lst Ann. Rep. U. S. Geol. 

 Sarv., pt. IV., 1901, 601-768, many excellent 

 plates and figures), giving description and ex- 

 planation to a stretch of the highest and 

 smoothest part of the Plains, from 150 to 200 

 miles east of the mountains, in Colorado, 

 Kansas, Texas and New Mexico. The largest 

 continuous area here included is that of the 

 Staked plains, between the Canadian and Pecos 

 rivers, but more attention is given to certain 

 smaller areas, separated by successive west-east 

 valleys and extending through Kansas and Col- 

 orado northward towards Platte River. The 

 strata of the High plains are chiefly silts, irreg. 

 ularly interstratified with gravel and sand in 

 linear arrangement, but in lines slightly diver- 

 gent and crossing. Silt is the most abundant 

 material, yet coarser deposits are so plen- 

 tiful that the whole loose accumulation is 

 sometimes referred to as the ' Tertiary gravel.' 

 This extensive deposit, in some places 500 feet 

 thick, is the product of aggradation by braided 

 or laced streams, whose load of material from 

 the mountains could not all be carried across 

 the gentle slope of the Plains. Evidence of 

 this origin is found not only in variable compo- 

 sition and irregular stratification, but also in 

 the trains of well-rounded gravel, derived from 

 the resistant rocks of the mountains, stretching 

 forward with the slope of the Plains, and be- 



coming finer textured eastward. The lacus- 

 trine origin of these strata, usually advocated 

 heretofore, but discountenanced by Gilbert and 

 Haworth, is considered by Johnson and again 

 rejected on good grounds. The fluviatile de- 

 posits mantle an uneven surface of older rock, 

 eroded by an ancestral drainage system. They 

 originally formed a vast ' debris-apron ' of 

 numerous laterally confluent river fans of long 

 radius, with continuous slope eastward from 

 the mountain base. Tne region was then a 

 fluviatile plain of great dimensions, similar to 

 that which to-day stretches southward from the 

 base of the Himalayas, in northern India, and 

 similar to the extensive piedmont fluviatile 

 plains of mountain waste that are so commonly 

 and appropriately associated with great moun- 

 tain ranges in one or another phase of their 

 maturity. But the High plains are now 

 trenched by the west-east valleys worn by the 

 successors of the streams that built the plains ; 

 this being the result of some change (preferably 

 the increase of rainfall that accompanied the gla- 

 cial period) whereby the capacity of the streams 

 to erode was restored. Moreover, the fluviatile 

 mantle has been worn away along two north 

 and south belts. One is the arid belt near the 

 mountain base, where vegetation is so scanty 

 that the small rainfall has sufficed to wear away 

 much of the river-made strata in the excavation 

 of lateral valleys. The other belt begins 100 or 

 200 miles further east, where the rainfall is 

 heavier and where the headward (westward) 

 growth of many streams is pushing back a bad- 

 land escarpment. Between these two degraded 

 belts the tattered remnants of High-plains 

 mantle are still smooth and uncut, because 

 under their subhumid climate they have a close- 

 knit cover of sod which has held fast under 

 their light rainfall. 



The dead-flat upland of the High plains is 

 lightly pitted here and there by shallow circular 

 depressions, up to 1,000 yards across. These 

 hollows are not due to wind action, for how- 

 ever dusty the gales may be on the arid belt 

 further west, the winds blow clear on the sod- 

 ded plains. Some of the hollows are crater- 

 like ; many are encircled by cracks and rims 

 of slightly settled grounds, and all except the 

 small ' buffalo wallows ' are regarded as sinks 



