276 



SCIENCE 



[Vol. XXII. No. 563 



the auditory organ of the locust, although in the Locusta 

 viridissima there are also others broadly clavate and sur- 

 rounded by a plainly delimited, granular substance. 



In Termes fiavipes there are no external ajjpendages to 

 suggest an auditory function, as there are in the locust 

 and in some other insects, there being here only a slight 

 concavity of the wall over the internal organ, and two or 

 three of the sensory pits scattered about the surface. If 

 the similar organs among members of the Orthoptera 

 have such a function, it seems not unreasonable to sup- 

 pose that such may be the use of these appendages within 

 the tibiae of our common white ants. 



Bat, however this may be, the legs of these insects merit 

 careful investigation by some eomj)etent observer, so situ- 

 ated that he may have access to all the luxuries of modern 

 microscopical research, most of which are at present 

 beyond my reach, my paper being, therefore, necessarily 

 superficial and imperfect. 



LETTEES TO THE EDITOE. 



jf\Correspondents are requested to be as brief as possible. The 

 writer's name is in all cases required as a proof of good faith. 



On request in advance, one hundred copies of the number con- 

 taining his communication will be furnished free to any corres- 

 pondent. 



The editor will be glad to publish any queries consonant with 

 the character of the iournal. 



The Osaqe River and the Ozark Uplift. 



Me. Arthur Winslow's account of the Osage river and 

 its meanders in Science for July 21, 1893, commenting on 

 my previous suggestion concerning the development of 

 that river in Science for April 28 of this year, has only 

 lately come to my attention in looking over papers accu- 

 mulated at home during vacation absence. It raises sev- 

 eral questions on which discussion may prove of interest. 



In exj^laining the existing meanders of the Osage and 

 other deep-valleyed rivers of Missouri and Arkansas, Mr. 

 Winslow maintains that the rivers had originally curved 

 courses consequent on the form of the land on which 

 they were initially formed; that these irregularities of 

 flow are still perceptible, although they have been in- 

 creased during the down cutting of the valleys; and that 

 the down-cutting of the valleys and the general sculptur- 

 ing of the region now going on is in consequence of an 

 uplift that was essentially comj^leted in Paleozoic time. I 

 am not sure as to my correct understanding of the third 

 point, although such appears to be Mr. Winslow's mean- 

 ing. 



The explanation that was suggested in my article in- 

 cluded a long lost beginning of river development in Mis- 

 souri; the attainment of an oldish topographic condi- 

 tion in the cycle of denudation preceding the pres- 

 ent cycle; and an inheritance by the rivers of a mean- 

 dering course, normally characteristic of the wide-open 

 valleys of the preceding cycle, in the deep-sunk valleys of 

 the present cycle. 



Mr. Winslow's first point— that the existing meanders 

 are simply exaggerations of initial consequent river 

 courses — seems to me inadmissable for several reasons. In 

 the first place, this involves the persistence through all 

 of Mesozoic and Tertiary time of relatively trivial jjeculi- 

 arities of river courses, begun on the surface of the car- 

 boniferous strata about the close of Paleozoic time. 

 It is certainly true that rivers are long lived, but it is 

 very unlikely that the land history of Missouri has been 

 so simple us to allow so extraordinary a perpetuation of 

 relatively small river features My reason for this opin- 

 ion is not simply an a priori objection to the opposite 

 view; but a careful examination of the developmental 

 changes of other rivers. In Pennsylvania, for example, 

 the changes in the course of rivers during a period cor- 



responding to that of the land history of Missouri has 

 been so great that I cannot think that the rivers of Mis- 

 souri still maintain any close trace of their ancient initial 

 courses down to these modern days. It is true that there 

 has been much greater oiDportunity for variation of river 

 courses among the tilted rocks of Pennsylvania than upon 

 the nearly horizontal strata of Missouri; but to conclude 

 that even in the latter region there have been no essen- 

 tial changes of river courses since the end of Paleozoic 

 time implies to my mind altogether too passive a concep- 

 tion of post-Paleozoic time. It is impossible to say ex- 

 actly what has happened, for the records are rubbed out; 

 but to conclude that practically nothing has happened in 

 the way of oscillation and warping and river change seems 

 to me the most unlikely of all plausible conclusions. 



In the second place, the postulate that the present 

 meanders are directly descended from originally irregu- 

 lar conseqiient courses does not well accord with the dis- 

 tribution of deep meandering valleys in other parts of the 

 world. They are not found in regions of one cycle of de- 

 velopment; that is, in regions that are now in process of 

 degradation following their first uplift. They characterize 

 regions which for other reasons — of which more below — 

 must be interpreted as having a composite topography; that 

 is, having topographic features produced in two or more 

 cycles of degradation. Moreover, the fact that the radius 

 of the valley meanders is greater where the rivers have 

 great volume is not consistent with the origin of the 

 meanders from a control so irrelevant to river volume as 

 the constructional inequality of the original land surface 

 must have been. 



Mr. Winslow's second point — ^that the existing mean- 

 ders are increased in sinuosity over some former condition 

 of meanders — seems to be an important correction to my 

 brief explanation. It is a point that I had not in mind 

 at the former writing; but in now recalling the form of 

 the meandering valley of the North Branch of the Sus- 

 quehanna in northeastern Pennsylvania, I see that the 

 correction ai^plies there as well as in Missouri. One 

 might at first suppose that if a meandering river were up- 

 lifted, it would tend to straighten out its course, on ac- 

 count of gaining a stronger current; but it also seems 

 possible that an even uplift with no change of grade (ex- 

 cept by the action of the river itself in cutting down its 

 channel towards the new base level) may even provoke 

 an increased meandering, instead of straightening out 

 former meanders. Professor J. C. Branner has in a letter 

 called my attention to essentially this interpretation of 

 certain deep meandering valleys in northern Arkansas. 



As to Mr. Winslow's third point — that the present val- 

 ley-making Missouri is the incompleted work of the 

 denudation begun at the end of Paleozoic time — I cannot 

 agree to this at all. Indeed, such a conclusion appears 

 to me so improbable, and so contrary to both local and 

 general evidence, that T fear it is not a correct statement 

 of Mr. Winslow's meaning. He says: "The sculpturing 

 of the topography [of Missouri] must have been uninter- 

 ruptedly in progress from the end of the Paleozoic to the 

 present time." He implies that the present altitude of , 

 the Osarks above the margin of the Tertiary strata in 

 southeastern Missouri is the same as the altitude that the 

 Osarks had above the waters in which the Tertiary strata 

 were deposited; thus excluding all chance of tilting and 

 local warf)ing since that time. Differential movements 

 havg been determined even as late as in Tertiary and 

 post-Tertiary time in the west; and there is good evi- 

 dence of similar late geological movements in the Appa- 

 lachians along the Atlantic slope. It therefore seems en- 

 tirelv improbable that Missouri should have taken an at- 

 titude at the close of Paleozoic time from which it has 

 not since significantly changed and entirely impossible, if 



