Jennings : A Botanical Survey of Presque Isle. 293 



current, or, (c) as a bottom- current, in either case depositing its load 

 as a "terrace." Presque Isle has, evidently, been initially formed as 

 a spit somewhere along the shore farther to the west and has been 

 slowly shifting its position to the east. It is claimed'" that at about 

 1800 A. D., a sand beach extended from the mouth of the run, one 

 mile west of the present " head " of the peninsula, and from there the 

 peninsula jutted out. A long narrow pond extended from the bay 

 between the peninsula and the mainland and as late as 1840 scows 

 were run in there from the bay for firewood. At that time the penin- 

 sula was said to be much wider at the western end than it is now. 



As now constituted Presque Isle is to be regarded as mainly the 

 joint product of four natural agencies somewhat modified in certain 

 particulars by man : (i) A littoral spit-forming current deviating 

 from the surf-line; (2) Conflicting currents tending to turn the spit 

 inward, thus forming a recurved spit or hook ; (3) The ridge-forming 

 surf of great storms from north and northeast; (4) The soil-accumu- 

 lating and soil-binding effect of the vegetation, aided by the drifting 

 power of the wind. 



Under the prevailing westerly winds there is a constant movement 

 of the beach-debris towards the east, both in the littoral current, as 

 before mentioned, and on the beach higher up. The breaking wave 

 as it rushes obliquely up the beach carries many particles of sand and 

 pebbles with it and, retreating obliquely in the other direction, leaves 

 them often several inches to the east of their former position. Dur- 

 ing a moderate surf on one occasion, with the waves striking the 

 beach at an angle, the writer observed rounded flat pebbles of about 

 an inch in diameter moving eastward in this manner. The marked 

 pebbles were not shifted with each wave but occasionally they would 

 be shifted a foot or more at one time, the general average during some 

 twenty minutes of observation being one and a half inches per wave. 

 Under such conditions it thus appears that certain of the looser, 

 more exposed pebbles would be transported the surprising distance 

 of about fifteen hundred feet in twenty-four hours, provided, of 

 course, that the pebbles remained in the same relative position on a 

 uniform beach. 



The general tendency during prevailing westerly winds is for this 



shifting beach-debris to be deposited at the extremity of the spit, as a 



'"Nelson, S. B. "Biographic Dictionary and Historical Reference Book of Erie 

 County, Pa.," p. 426, 1896. 



