1866.] 31 tPorter. 



the figures has, as yet, been unsuccessful. The following facts were 

 collected and reported by the committee. 



Positio7i of the Rocks. — The Susquehanna river below the dam at 

 Safe Harbor, Lancaster County, is filled with a multitude of rocks 

 and rocky islets, various in size and extent, between which, the fall 

 being considerable, the water rushes, forming a series of rapids and 

 eddies, navigable only by canals. The width of the stream at this 

 point is scarcely less than a mile, and the jurisdiction of Lancaster 

 County extends to low-water mark on the York County shore. 

 Among these rocks are the two in question. 



The larger one. A, lies a full half mile below the dam, in a line 

 nearly due south from the mouth of the Conestoga. 



The smaller one, B, is situated about 250 yards further up, in the 

 same line, at a distance of some 400 or 500 yards from the eastern 

 shore. 



The currents around both rocks are strong and swift. 

 Their Character. — Each rock is composed of several masses over- 

 lying each other at an angle of 45° down stream, the lines of divi- 

 sion running east and west, the southern crest being the highest. 

 They consist of gneiss, which is rather friable within but hard on 

 the outside. The surface is roughened by grains of quartz, and here 

 and there are seen distinct veins of the same material. The portions 

 facing up stream have been rounded and worn smooth by the action 

 of ice and drift-wood during the high freshets of early spring, as may 

 be inferred from the logs piled upon and around them, and from the 

 striae or grooves on the larger rock, produced probably by angular 

 pieces of stone imbedded in cakes of ice. Each rock has also, ex- 

 tending a little distance below it, a tongue of land on which grow 

 dwarf oaks, dogwoods, and a few herbaceous plants. 



Their Dimensions. — Rock A measures through the centre, from 

 north to south, 82 feet, and from east to west 40 feet. It slopes 

 gradually upward from north to south ; the lowest part being 9 feet, 

 and the highest 16 feet above low-water mark. This rock is said to 

 be the highest in the river near Safe Harbor, and from its flat sum- 

 mit the prospect is extensive and beautiful. 



Rock B measures, from east to west, on the north side, 20 feet ; 

 on the south side, 29 feet 8 inches ; from north to south, on the east 

 side, 12 feet 9 inches; on the west side, 8 feet 6 inches. The 

 height on the west side above low-water mark is 6 feetj of the east 

 side, 12 feet 9 inches. 



From the east side a huge mass has been broken off, perhaps 



