BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 28, pp. 335-346, PLS. 18-20 JUNE 11, 1917 



SUBMEEGED "DEEPS'' Ij^ THE SUSQUEHANNA RIVEE ^ 



BY EDWARD B. MATHEWS 



{Read lefore ihe Society December 28, 1916) 



CONTENTS 



Page 

 Introduction 335 



Geology of the region 336 



Detailed description of the "deeps" 337 



Location of the "deeps" 337 



One and three-fifths miles above Safe Harbor, Pennsylvania 339 



"Deep" at McCalls Ferry 339 



Mingua or Holtwood 341 



Below Culleys Falls 342 



Above Fites Eddy 342 



Origin 342 



Age of "deeps" 345 



Conclusion 345 



Introduction 



Prior to the construction of the dam and power plant at McCalls Ferry, 

 Pennsylvania, a careful survey of the river bottom was made by sound- 

 ings under the direction of Mr. Gary T. Hutchinson, Ghief Engineer of 

 the McGalls Ferry Power Gompany. The results of this survey, so far 

 as they were of scientific interest, were placed at the disposal of the 

 writer, who, as consulting geologist, made an examination of the river 

 bottom laid bare by the construction of the coffer dam. The portion of 

 the survey under present consideration extends from Turkey Hill, 3 miles 

 south of Washingtonboro, Pennsylvania, to tide near Port Deposit, Mary- 

 land. Throughout the entire distance the river flows in a flat-bottomed 

 rock gorge with stream-cut walls, which rise to the general level of the 

 Piedmont Upland. The river bottom is generally studded with numerous 

 rocky inlets, which rise but a few feet above the normal river surface, 

 and a few steep-sided islands, whose wooded tops may reach 100 feet 



Manuscript recpivod by the Secretary of the Society Feltniary 19, 1917. 



(335) 



