period of time. This period must be sufficient to cover the main cyclic events 

 associated with the seasons. Repeated surveys should cover each of the 

 seasons of a yearly cycle. In addition, survey density and timing suitable to 

 document the effects of extreme events, such as major storms, floods, and 

 hurricanes, are also desirable. Study of long-term cycles by repetitive surveys 

 is not widely practiced because of the expense and continuing commitment 

 needed to obtain sufficient data. 



Historical maps, charts, and aerial photographs are important sources of 

 geologic information. A valuable source of these items is the National Ocean 

 Service (NOS) and its predecessors. Survey data extending back 150 years 

 are available for many areas, and preliminary charts of considerably larger 

 scale and detail than the published versions can be obtained from the NOS 

 archives. These historic sources are of great value in revealing long-term 

 trends. Some sources for historical and recent aerial photography and maps 

 are listed in Fulton (1981). 



Data on intermittent noncyclic events are usually difficult or impossible to 

 obtain. In particular, baseline data of conditions immediately before the event 

 are often nonexistent because there is typically insufficient advance warning to 

 organize and conduct an adequate survey. However, aerial photographs can 

 often be obtained even with fairly short notice and are valuable in showing 

 conditions before an event, especially in the shore zone. Post-event surveys 

 should be conducted as soon as the affected area becomes accessible. 



Information regarding past events can often be found through a com- 

 bination of field and laboratory tests. These include a variety of stratigraphic 

 and sedimentologic techniques, such as the analyses of sedimentary structures, 

 grain size, sediment composition, heavy minerals and fossils, and the 

 radiometric dating of organic remains in sediment deposits and of other iso- 

 topes of natural and human-derived sources. These techniques, in addition to 

 archeologic and pedologic ones, are of value in working out past environmen- 

 tal changes and events over a variety of time scales, although some parts of 

 the geologic record may have been obliterated. 



Literature sources on coastal features and processes, many containing 

 historical information, are abundant, but a considerable research effort is 

 needed to cull out pertinent works. In a recent computer-assisted literature 

 search, over 1,400 items were listed under the key words "coastal geology," 

 "coastal geography," "coastal geomorphology," and "coastal classification." 

 Most had been published since 1970. Selected key sources of coastal 

 engineering information, including meteorology and climatology, water levels, 

 wave and currents, ice, beach erosion and littoral transport, topography and 

 bathymetry, and geology and geomorphology, are described in Chu, Lund, 

 and Camfield (1987). Historical geomorphic data can also be acquired from a 

 variety of sources (Trimble and Cook 1991). Local records such as tax 

 assessments, deeds, and local surveys may also be useful (Fulton 1981). Fur- 

 thermore, there are many unpublished sources of coastal information that can 

 be sought from government agencies, universities, and private firms. 



Chapter 1 Introduction 



