490 PROCEEDINGS OF THE ALBANY MEETING 



easily accounted for by such a flood, on a grander scale, attending the melting of 

 the ice-sheet of the Wisconsin stage in Dakota.* 



2. It is not difficult to extend the analogy also to the streams draining the ice- 

 sheet at the end of the Kansan stage of the Glacial epoch, and thus explain the 

 vastly wider silt-sheets, known as loess or " upland loess." Such a view will go 

 farther toward explaining the massive structure, the wide stretches of flat surface, 

 and yet considerable range of level of that problematic deposit. Of course, we 

 would not be suspected of ignoring the results of subsequent erosion and creeping, 

 nor of the frequently important influence of fcolian action. 



3. We have in this phenomenon another obstacle to the easy calculation of the 

 discharge of rivers by simply noting the rise of water upon gauges ; for the chan- 

 nel is vastly widened, so that the gauge ceases to be the proper measure of the 

 cross-section on that account. But a still more important difficulty results from the 

 temporary filling of the regular channel. This is likely to be overlooked, and yet 

 the fact of its occurrence seems clearly established. The great flood of 1881 was 

 doubtless exceptional in degree, yet it shows the working of conditions efficiently 

 present in any flood where the water overflows the banks. It will be noted that 

 this tendency is in tiie opposite direction of the })henomenon first noted in this 

 paper. It seems that as long as the water remains in the banks a flood cuts out 

 at the bottom of the channel, but as soon as the water begins to overflow, espe- 

 cially when a considerable current begins to traverse the bends of the stream, the 

 flow in the channel proper is checked and rapid deposition begins; hence the dis- 

 charge of water will be much less than would l)e inferred from the reading of the 

 gauges. 



The f()llowing paper was read by the author: 



FORT CASSIN BEDS IX THE CALCIFEROUS LIMEhTONE OF DUTCHESS COUNTY, 



NEH' YORK 



BY W. B. DWIGHT 



[ A bstracQ 



Hitherto, in the large and unique assemblage of fossils of the Calciferous lime- 

 stone of Dutchess county, New York, no special relations to the remarkable fauna 

 of the Upper (?) Calciferous beds of Fort ('assin, Vermont, have been discovered, 

 unless in the relative aljimdance and prominence of cei)halopods. 



This is easily explained by the fact that the characteristics of the Dutchess County 

 cephalopods, especially the frequency of the septa, and the complicated forms of 

 the septal necks show that the main CaUtiferous beds (conveniently designated the 

 Cyrtoceras vassarinum beds) of Dutchess county are much older than the Fort 

 Cassin beds. 



A recent careful study reveals the presence in Dutchess county of a layer quite 

 persistent throughout the nearly 30 miles of extent of fossiliferous calciferous strata, 

 which contains a peculiar fauna entirely difl'erentiated froiii the fauna of the main 

 or Cyrtoceras vassarinum beds. It is, in places, absolutely crowded with fossils, 

 largely fragments of small trilobites, but it lacks cephalopods almost entirely. 



* Missouri Geological Survey Report, vol. x, p. 207. 



