Environmental and Geologic Factors Affecting 

 Coasts 



Broad classifications of morphologic type can be identified at coastlines 

 around the world. A partial listing includes barrier, strand plain, deltaic, mud 

 flat, volcanic, rocky, reef-fringed, and estuarine 1 coasts (Carter 1988; Mossa, 

 Meisburger, and Morang 1992). Within each of these major groups, 

 however, a number of distinctive environments can be distinguished when 

 examining the coast in cross section and in plan view. Some of these environ- 

 ments are common to many types of coasts. Figures 2,3, and 4 show exam- 

 ples of the types of environments found at coasts within some of the 

 morphologic groups. 



Figure 2. A three-dimensional view of some features commonly associated 

 with a barrier island system, including the back barrier, overwash 

 fans, and lagoons 



The geomorphic variability and geologic evolution of the coast are influ- 

 enced by an array of environmental factors. A partial listing of the factors 

 that influence coasts over varying time scales includes climate, wind, and 

 cyclonic disturbances, waves, tides, storm surges, currents, relative sea level, 

 lithology and weathering, erosion and transportation, sediment supply, coastal 



1 Geologic terms are defined in Appendix A, "Glossary," at the end of this report. 



Chapter 1 Introduction 



