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4 Laboratory Techniques and 

 Approaches 



Laboratory Observation and Experiment 



The characteristics of samples obtained in the field can be further analyzed 

 in the laboratory. Some properties that are commonly examined include: 

 (a) sediment properties, such as grain size, shape, and density, mineralogy, 

 and heavy mineral type and content; (b) stratigraphic properties, which can be 

 characterized using core description, preservation, and analysis techniques; 

 and (c) geochronological history, obtained from radiometric dating and a 

 variety of relative dating approaches. In order to achieve maximum benefits 

 from laboratory analyses, the coastal scientist should be cognizant of the 

 limitations and variance of the precision and accuracy of each test and 

 procedure. 



Laboratory Analysis of Sediment 



Sediments are solid fragmental materials that originate from the weathering 

 of rocks and are transported and deposited by water, air, or ice. Coasts that 

 are comprised of sediment, in contrast to rock, are highly dynamic and are 

 likely to have a complex geologic history. Analyses of the sediment 

 characteristics, such as particle size, mineralogy, and heavy mineral content 

 can reveal information about sources of materials, depositional environment, 

 littoral processes, and the nature of coastal landforms. This knowledge of 

 sediment characteristics, in turn, may be useful for predicting sediment 

 movement during storms, the nature of seafloor features, and the geologic 

 history of the area of investigation. 



Sediments can be classified into size range classes. Ranked from largest to 

 smallest, these include boulders, cobbles, gravel, sand, silt, and clay 

 (Table 9). The particle size is often expressed as D, or the diameter in 

 millimeters, and sometimes includes a subscript, such as D 84 , to indicate the 

 diameter corresponding to the listed percentile. As an alternative, grain size 

 is often expressed in phi (</>) units, where = -log 2 D (Hobson 1979). This 



Chapter 4 Laboratory Techniques and Approaches 



