reason, clear core liners are preferable for making core logs and selecting 

 representative samples . 



157. Ideally, visual and physical access to cores is best obtained by 

 splitting the cores lengthwise to expose the cored section. However, in the 

 field this is undesirable because split core tubes have little structural 

 strength, and even when rejoined and taped together, are difficult to handle 

 and ship to the laboratory without breaking, loosing material out the sides, 

 or causing serious disturbance of the contents. Thus, field procedures for 

 viewing potential borrow material are limited by a need to maintain the integ- 

 rity of the core container. 



158. The normal procedure in field sampling of cores is to obtain top 

 and bottom samples from the ends of the tube before they are capped, and to 

 obtain samples between the ends by using a 1- to 2-in.-diam hole saw to bore 

 through the tube wall and provide access for removing a small sample. After 

 this, the hole is sealed by tape. Representative samples should be obtained 

 from each lithologically distinct layer identified in the visual logging pro- 

 cess. In cases where the core container is opaque, no precise log can be 

 made. The best way to obtain information about lithologically distinct sedi- 

 ment units in the core is to drill a number of arbitrarily selected holes with 

 a 1/2- or 3/4-in. flat bit to permit visual inspection, be able to approximate 

 the location of boundaries, and select sample positions. 



159. The objective of sample analysis in the field is to obtain litho- 

 logic information on the material contained in the cores for inclusion in core 

 logs and identification of possible borrow material for the project beach. 

 Primarily, samples are examined visually to determine pertinent characteris- 

 tics such as size distribution and composition in terms of relatively broad 

 categories. For this purpose, a hand lense and size comparison chart are use- 

 ful aids. In addition, samples that appear, on visual examination, to be pos- 

 sibly suitable as fill material should be further analyzed to obtain data on 

 their size distribution characteristics by more accurate means than visual 

 inspection. This can be done by using small 3-in.-diam sieves to separate 

 small samples into appropriate size fractions which are then weighed to deter- 

 mine the percent weight of each size fraction. Minimal equipment needed for 

 this procedure is a drying oven of 1-ft 3 capacity or more, but small enough to 

 be portable, 3-in.-diam sieves covering the Wentworth sand size ranges at 

 1/2-phi intervals, and a small top-loading electronic balance with a precision 



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