July 12, 1901.] 



SCIENCE. 



71 



down-valley shifting and the broadening of the 

 meander belt are well shown by the pattern of 

 the toe-taps of alluvium that are added, right 

 and left, to the flood plain lobes as the meanders 

 grow and shift, as in the accompanying figure. 



All these systematic changes are directly shown 

 by a comparison of the river banks in black 

 and red on the new edition of the map ; the 

 wasting banks being systematically located on 

 the outer and down- valley side of the channel, 

 as indicated by heavy lines in the above dia- 

 gram. Sheet 14 includes the remarkable ser- 

 pentine meanders near Greenville, where the 

 increase of radius and arc and the dowm-valley 

 shifting are beautifully shown. Sheets 17, 18 

 and 19 include a number of curves in the neigh- 

 borhood of Vicksburg, where the river has de- 

 stroyed the old levees, thus necessitating the 

 construction of new ones further back from the 

 bank. The bends below Baton Kouge (sheet 

 25) exhibit relatively small change of position. 



THE KIVER SPEY. 



The physiography of the Spey, a river flow- 

 ing eastward from the Highlands of central 

 Scotland to the North sea, is considered by 

 Hinxman (' The River Spey,' Scot. Geogr. Mag., 

 XVII., 1901, 185-193). A number of the items 

 presented are of interest, but the plan of the 

 article does not imply a comprehensive view of 

 the natural history of rivers. " The Spey val- 

 ley for the greater part of its extent may * -^ * 

 be regarded as the result of the slow erosion of 

 the river, continued since early Paleozoic 

 times " ; this suggests altogether too great an 

 antiquity ; the incision of the Spey valley, and 

 of all the existing valleys, glens and straths of 

 Scotland, beneath the general level of the 



Highland summits, is probably not older than 

 Tertiary, and certainly not older than middle 

 Mesozoic time. The valleys of " the river and 

 its principal tributaries * * * belong to a very 

 early period in the history of the earth. That 

 they existed before the Old Red sandstone 

 age " is known, because patches of that forma- 

 tion still remain in them here and there ; a 

 safer statement would be that an uneven land 

 surface, presumably a region of hills and val- 

 leys, was buried by the Old Red, and that some 

 of these ancient valleys have been re-exca- 

 vated ; but it is very improbable that the main 

 and branch valleys of the Spey system are in 

 any close degree coincident with any single 

 ancient valley system. Indeed, much may be 

 said in favor of the initiation of these and cer- 

 tain other Highland valleys on a land surface 

 that was deformed by the tilting and faulting 

 which disturbed the Old Red itself. No special 

 consideration is given to the stage of develop- 

 ment of the Spey in pre-glacial time, or to the 

 amount of change produced by glacial action, 

 destructive or constructive ; bvit certain fea- 

 tures of the existing river are presented. One 

 is the diversion of a small upper part of river 

 Feshie from the Dee system to the Spey ; the 

 diversion is ascribed to normal retrogressive 

 erosion, but it is not shown that the capturing 

 stream had any special advantage over the 

 captured, and no account is taken of glacial 

 action.* Reference is made to the temporary 

 enlargement of the Spey by waters from Glen 

 Spean, on the w^est, when the lower course of 

 the Spean was obstructed by ice in the Glen 

 Roy district ; but that the Pattack and several 

 other barbed headwaters of the present Spean 

 were preglacial members of the Spey system is 

 not considered. Special emphasis is given to 

 the abnormal slope of the Spey ; the upper 

 course falls 327 feet in 14 miles, the middle 

 course falls 215 feet in 40 miles ; and the lower 



* According to the Ordnance map, a gorge on the 

 Feshie two miles southeast of Rnigb-fionntaigh would 

 seem to inark the site of the divide between Spey and 

 Dee before the diversion ; and the diversion appears 

 to have been associated with some glacial control. 

 The gorge is not situated where it should be if the 

 upper Feshie had been diverted by retrogressive 



