GEOLOGICAL CHARACTER AND MINERAL RESOURCES 

 OF SOUTH CENTRAL LAKE ERIE 



by 



S. Jeffvess Williams and Edward P. Meisbtirger 



I . INTRODUCTION 



Presque Isle Peninsula is a classic example of a compound recurved sand- 

 spit, which extends 4 kilometers into Lake Erie and about 10 kilometers along 

 the Pennsylvania shoreline. Because of its position and morphology, Presque 

 Isle acts as a natural offshore breakwater for Erie Harbor, blocking the pre- 

 vailing winds and waves from southwest to northwest. However, Presque Isle 

 has experienced severe erosion on the straight "neck" segment, because of its 

 exposed position, while the eastern distal end has undergone continual growth 

 in length and width. Presque Isle is important not only to the service of Erie 

 Harbor, but also as a recreation resource to 3 to 4 million annual visitors. 

 Because of this value several engineering plans have been implemented during 

 the past 40 years in an attempt to diminish erosion and maintain the integrity 

 and position of Presque Isle. 



Presque Isle was first surveyed by Army engineers in 1819 because of ero- 

 sion problems, and it became a federally authorized beach erosion project in 

 1824. Historically, severe erosion has always plagued the narrow neck part of 

 Presque Isle. On at least four occasions waves have breached the neck and cre- 

 ated inlets that separated the peninsula from the mainland; each time, how- 

 ever, the inlets have been closed either by natural processes or by Federal 

 and State action. Serious interest in maintaining Presque Isle for recreation 

 purposes and the protection of Erie Harbor began to grow in the late 1940' s. 



The first comprehensive coastal engineering plan, which began in 1956, 

 consisted of constructing a system of groins combined with sandfill for 

 beach nourishment along the western side of the peninsula mainland out about 

 two- thirds the length of the peninsula. The sandfill was derived from borrow 

 pits within Erie Harbor and was considered suitable but the mean grain was 

 smaller than the native beach material. Because of this the sand was very 

 unstable in the normal littoral environment, causing subsequent erosion and 

 the rapid removal of the nourished shore. There have been numerous emergency 

 fills and all but one, which was done in 1965, failed to maintain the desired 

 beach width and height because the fine sand placed was highly susceptible to 

 erosion. The 1965 nourishment plan included an experimental phase that 

 placed coarse sand with a mean size of about 0.4 phi (0.75 millimeter), in 

 comparison to native grain size of 2.1 phi (0.23 millimeter), on a 350-meter- 

 long stretch of shore between groins No. 2 and 3 where the greatest erosion 

 occurred (Berg and Duane, 1968) . This fill was unique in that it was derived 

 from a State-leased area about 13 kilometers offshore from the project. Sam- 

 pling and profiling of the groin compartment following the coarse sandfill 

 operation indicated that the shore experienced little loss of sand and main- 

 tained a stable profile. Berg and Duane 's (1968) findings proved that the 

 use of fill with a coarser size distribution than the native sand, but includ- 

 ing all the native profile sizes, can be an effective means of both stabilizing 

 the shore and providing a recreational resource. 



