station. Table 2 gives the dates when each of the 34 stations were pro- 

 filed, along with the daily mean lake level, and the distance of the 

 shoreline from the base monument. Negative niombers in the table indicate 

 that the shoreline had passed landward of the base monument by the given 

 date. 



3. Profile Procedures . 



In 1967, the profiles were measured by a leveling cart. A leveling 

 rod was attached to a four-wheel cart which was winched ashore. Every 

 5 meters the cart was halted and the elevation determined by an engineer's 

 level located onshore. When the cart reached shore it was pulled by a 

 Jeep down the beach to the next station and towed back offshore by boat. 

 This method limited coverage to depths of less than 5 meters and required 

 a moderately wide, unobstructed beach for efficient operations. In sub- 

 sequent years, echo sounding was used to measure the outer part of the 

 profile to a depth of 15 meters, but instrument leveling was still used 

 to give overlapping coverage in shallow water and extend the profile to 

 the dry beach. Since this report is concerned only with changes in shore 

 erosion, no further discussion is made of the echo soundings or outer 

 profiles. Instead, inner and outer profiles will be combined in a later 

 report addressing the manner in which the entire active profile adjusted 

 as lake levels rose (Hands, in preparation, 1979) . 



After 1967, the elevations on the inner profile were determined at 

 the top and toe of the bluff (if one existed), the upper and lower limit 

 of the swash zone, and at 5-meter intervals between the dune and the first 

 longshore bar, using the engineer's automatic level. Horizontal control 

 was by tag line, except in 1976 when distances were obtained from stadia 

 intercepts using the "three-wire technique"--the procedure most commonly 

 followed by military topographic surveyors. Reference monuments were 

 tied to existing bench marks and second-order control stations surveyed 

 by National Ocean Survey (NOS) in 1973. Additional vertical reference was 

 obtained during profiling operations using a system of water level gages, 

 water surface rod-readings, and a portable stilling well placed near the 

 shoreline at each station. Profile accuracy in the horizontal is on the 

 order of 1 meter from the base monument along the original .azimuth. Ver- 

 tical profile accuracy is about ± 5 centimeters. 



III. TERMINOLOGY 



Precise definitions are given that refine the meaning of several 

 familiar terms used in this report. Submergence refers to the sinking 

 of a coastal area relative to the mean water surface regardless of cause. 

 Submergence can result from either subsidence of the shore or increases 

 in the elevation of the water surface. Emevgenae refers to the opposite 

 relative displacement, and when expressed numerically, both emergence and 

 submergence refer to length measurements in the vertical. Coastal 

 planners and property owners are often more interested in the resulting 

 horizontal change in shoreline position: shoreline retreat is any land- 

 ward migration of the shoreline; advance is the lakeward migration of 

 the shoreline. 



