32 



SCIENCE. 



[Vol. XXII. No. 546 



thin covering of the rocks of that formation; that these rocks 

 were subjected to subareal erosion before and probably during 

 the Pennsjlvanian epoch and that coal-measure strata probably 

 never covered the dome of the uplift ; that since this time the 

 region has been continuously above water level. According to 

 this record the sculpturing of the topography must have been 

 uninterruptedly in progress from the end of the Paleozoic to the 

 present time. 



Professor Davis sees evidence in the character of the relief that 

 denudation progressed to such a degree that the present upland 

 was a lowland — " well into Tertiary time, and that the new 

 trenches of the Osage and its neighbors were begun in conse- 

 quence of an uplift somewhere about the close of Tertiary time" 

 — as opposed to tliis conclusion we have the fact that the Ozark 

 plateau is at present much above the limits whi;h we recognize 

 Tertiary seas to have reached. The altitude of the Tertiary 

 margin of the Mississippi embayment in southeastern Missouri is 

 under 400 feet A. T. The summit of the Ozarks is, however, as 

 much as 1,700 feet above sea level and the greater portion of the 

 upland is over 1,000 feet, and was consequently at least 600 feet 

 above the Tertiary sea level. Could a country having this alti- 

 tude above contiguous seas be in a base-leveled condition ? Fur- 

 ther, another fact to reconcile vvith this hypothesis is the finding 

 of certain chert gravels fringing the Osage and other valleys of 

 the Ozarks, not very high above the present channels of the 

 streams, which we provisionally correlate with the Orange sands 



pect certain peculiar features of topography to prevail. Thus, 

 with a stream not yet at base level we should look for its channel 

 to constantly hug the hill on that side of the stream which is im- 

 pinged by the current; here we should expect to find bluffs de- 

 veloped and maintained; conversely, on the "lee" side of the 

 stream, we should expect to find such flat alluvial plains as exist, 

 with comparatively gentle slopes thence to the uplands. Further 

 we should expect to find the points or promontories of uplands 

 which are nearly surrounded by the loops of the river, sloping 

 somewhat gradually towards their ends and not terminating in 

 bluffs. These features are pronounced, in part at least, to a 

 striking degree along the Osage. They are details which could 

 not be brought out on the maps of the scale of those thus far 

 made of the Osage country, but the constancy with which the 

 stream clung to the bluffs on the impinging side was impressively 

 seen during the recent trip along that river, while the form of 

 the projecting uplands is well illustrated by the following copy of 

 a portion of a map of Grand River, one of the tributaries of the 

 Osage, recently surveyed by Mr. C. F. Marbut, of the Missouri 

 Geological Survey. On the hypothesis advanced the precipitous 

 slopes characterizing the upstream sides of the hills here shown 

 are the result of the sapping action of the stream; the gradual 

 slopes of the downstream sides ate primarily a combined result 

 of the lateral movement of the channel accompanying the expan- 

 sion of the meanders, and of its downward movement by corrosion. 

 It is true that similar features would result with the trench of 



Scale, 1 mile to 1 inch. 



MEANDERS OF GRAND RIVER, A 



Contour-interval, 20 feet, 



OV THE OSAGE. 



of the Mississippi, of probable late Tertiary a!>;e. The.^e imply 

 the existence of such valleys with approximately their present 

 phases in late Tertiary times. Still, as the correlation of these 

 gravels is as yet confessedly quite hypothetical, this considera- 

 tion cannot claim much weight. 



Another hypothesis which has been thought by us to suggest 

 an explanation of the sinuosities of these streams, has gained 

 some strength through the observations of a recent boat trip down 

 the Osage River, from Osceola to its mouth. If we take the case 

 of a stream with a slightly sinuous course and of considerable 

 declivity, moderately incised in a nearly fiat, or even in an un- 

 dulating country of horizontal strata— such as might exist in a 

 newly emerged land surface soon after its emergence— we can 

 understand that meanders will tend to develop somewhat as they 

 do in the alluvial plain of a stream which has reached base level. 

 Where the current impinges sapping will increase the convexity 

 and the sinuosities will become more pronounced Inasmuch, 

 however, as the declivity of the stream is great, corrosion is still 

 active and the channel thus sinks vertically at the same time 

 that it moves laterally, and in this respect its development will 

 differ from that of a channel in a base-leveled alluvial plain. As 

 a natural result of this process we can see how the stream will 

 eventually shape foi; itself a tortuous and steep-sided valley, 

 with very narrow flood plains until the channel has reached base 

 level, when corrosion will cease and lateral degradation will in- 

 crease; then, swinging from bluff to bluff in a secondary system 

 of sinuosities, the stream will sap its bordering hills and widen 

 its flood plains. If this explanation be a true one we should ex- 



previously developed meanders in the manner suggested by Pro- 

 fessor Davis ; for we cannot conceive of a meandering channel 

 sinking absolutely vertically. Lateral degradation and move- 

 ment must always accompany corrosion and vertical lowering of 

 the channel ; if the meanders existed originally their shapes must 

 have been modified to the present forms. Hence the effects cited 

 would seem to be attributable to one of two causes, or to both 

 combined. The question is whether one is not all sufficient; 

 whether a previous base-leveled condition is a necessary assump- 

 tion. 



THE BOOM OF THE PRAIRIE CHICKEN. 



BY T. A. BEREMAN, MOUNT PLEASANT, IOWA. 



How many of your readers ever saw a prairie hen, or, as they 

 are commonly called in the west, the "prairie chicken?" 

 Doubtless many have seen dead ones, killed and shipped for the 

 market, btit I dare say that many of your younger readers, es- 

 pecially those living in the cities and towns, have rarely seen a 

 live one. In 1845, when I came to Iowa, and for several years 

 afterwards, they could be seen here in flocks of thousands to- 

 gether. But now there are only a few remnants of them left; 

 here and there, in isolated fields, some dozen or two survivals 

 have been permitted to remain. They are what is called the 

 pinnated grouse of North America, and were formerly inhabitants 

 of New Jersey, Pennsylvania and Kentucky, and all the western 

 prairie country. 



But at present I only desire to call attention to the matinee 

 songs of this wild bird of the prairie. Some morning in the 



