TITLES AND ABSTRACTS OF PAPERS 151 



has occurred the farmer finds it, instead of beneficial, almost as damaging as 

 scour. Finally, if all the silt of the river were caught and spread over the 

 floodplain, it would take literally centuries to build the land up above the 

 present high-water mark, and perhaps by that time the natural high water 

 would be still higher. 



On the other hand, as I have traveled about over the bottom lands I have 

 frequently allowed myself to dream of a system of low and gradually raised 

 cross-levees that would catch a considerable part of the silt. It costs but a 

 small fraction as much to build a levee one-third of a foot high as it does one 

 twenty feet high. Such levees are needed for highways anyway. Modern 

 dredges, which move silt thousands of feet at low cost, could be called in to aid 

 in the processes of silting and levee building. Several other beneficial effects 

 might be noted,' but at the end of every such dream I have had to admit that 

 the most carefully devised plan would be almost, if not quite, chimerical. 



Further remarks were made by Professor Lane. 



"DEEPS" IN THE CHANNEL OF THE LOWER SUSQUEHANNA RIVER 

 BY EDWARD B. MATHEWS 



(Abstract) 



The purpose of the paper is to present to the Society and place on file cer- 

 tain facts regarding the bottom of the Susquehanna gorge disclosed by sound- 

 ings and withdrawal of the water incident to the construction of the McCalls 

 Ferry Dam. 



The special scientific interest of the phenomena described lies in the fact 

 that these "deeps" lie south of the generally accepted limits of the ice-sheets, 

 in a region of more or less homogeneous rock, which gives little or no evidence 

 that it has undergone sharp warping since the cutting of the river gorge. 



These facts and the peculiar features of the "deeps" make the application of 

 the usual explanations for such phenomena doubtful, if not Impossible, in the 

 present case. 



Presented in abstract extemporaneously. 



NEW TEST OF THE SUBSIDENCE THEORY OF CORAL REEFS 

 BY REGINALD A. DALY 



(Abstract) 



The floors of many atoll and barrier lagoons situated in the trade-wind belts 

 fail to show the transverse profiles expected if the enclosing reefs were formed 

 as Charles Darwin imagined. Where the dominant winds blow from one 

 quarter, the lagoon bottoms should, according to the subsidence theory, be 

 differentially aggraded in the general direction of those winds. But the ocean 

 charts clearly show the lagoons so i)laced to have practically the same depths 

 to windward and to leeward of their respective centers. 



Presented in abstract extemporaneously. 



XI — Bull. Geol. Soc. Am., Vol. 2S, 1916 



