associated geological principles (Figure 1). These general categories overlap. 

 Furthermore, within each of the categories, certain time scales may be of 

 particular importance for influencing coastal changes. For example, tidal and 

 seasonal changes are significant in modern studies, and Holocene sea level 

 history is important in paleoenvironmental studies. Tidal fluctuations are 

 difficult to detect in studies of paleoenvironmental changes, and sea level 

 typically changes too slowly to be an important factor in modern process 

 studies. 



Several lines of inquiry are available to assess the geologic and geomorphic 

 history of coasts. One means of acquiring coastal data is through field data 

 collection and observation. These data may be numerical or non-numerical, 

 and may be analyzed in the field, laboratory, or office. Laboratory studies 

 are used to collect data through physical model experiments, such as in wave 

 tanks, or to analyze geological properties of field data, such as grain size or 

 mineralogy. Office studies include interpretation of historic maps, 

 photographs, and references, as well as analyses and numerical simulation of 

 field, laboratory, and office data. Typically, the best overall understanding of 

 environmental processes and the geologic history of coasts is acquired through 

 a broad-based combination of techniques and lines of inquiry. 



The quality of the results depends on several factors. Among these is the 

 use of existing data. If secondary data sources (i.e. existing maps, 

 photography, and literature sources) are limited or unavailable, assessing the 

 geologic history will be more difficult, more costly, and typically more 

 inaccurate. Consequently, before initiating detailed field, laboratory, or office 

 studies, thorough literature review and search for secondary data sources 

 should be conducted. This report lists sources and agencies that can be con- 

 sulted in searches for secondary data of various types. 



The quality of the research equipment, techniques, and facilities also 

 influences the quality of the evaluation of geologic and geomorphic history. 

 For example, echo-sounding and navigation instruments used to conduct 

 bathymetric surveys have recently been improved. If such equipment is 

 available, the mapping of geologic and geomorphic features can be extended 

 further seaward to a higher degree of accuracy than was previously possible. 

 It is important that the coastal geologist and engineer stay abreast of new 

 techniques and methods, such as remote sensing and geophysical surveys, 

 computer software and hardware developments, and new laboratory methods. 

 For example, recent developments in Geographic Information Systems (GIS) 

 enable the coastal scientist to analyze and interpret highly complex spatial data 

 sets. This report describes some recent developments and techniques that are 

 used in the analysis of coastal data sets. 



Scientists must recognize certain problems and assumptions involved in 

 data collection and analyses and make adjustments for them before making an 

 interpretation. It is critical to account for various sources of error in 

 preparing estimates of coastal changes and acknowledge the limitations of 



Chapter 1 Introduction 



