CONTENTS --Continued 



FIGURES 



Page 



1 Location of study area 7 



2 Historic changes in annual mean water levels on 



the Great Lakes, 1860 to 1978 9 



3 Profile stations in vicinity of Pentwater jetties 12 



4 Station location in the study area 13 



5 Terminology of retreat 16 



6 Terminology of vertical and horizontal shoreline changes .... 17 



7 Different formats depicting changes in the shoreline 



adjacent to the Pentwater jetties 18 



8 Change in shoreline position 19 



9 Time changes in positions of various contours intersecting 



the beach face 22 



10 A fairly typical inner profile 24 



11 Encroachment versus recession as a cause of shoreline retreat. . 26 



12 A shoreline indentation opposite the Little Sable Point light 



in August 1975 introduces variability in shore retreat as it 



migrates alongshore 28 



13 Views of shoreline undulations which sometimes form where 



the inner bar merges with the shore 29 



14 Distributions of measured retreat rates 31 



15 Lake Michigan hydrograph showing changes in lake level 



between survey periods 31 



16 Submergence versus retreat 32 



17 Historic shoreline changes in the vicinity of Pentwater jetties. 36 



18 Comparison between rates of historic and recent recession. ... 38 



