split for detailed logging. Log descriptions should include texture, color, 

 organic matter, bedding features, and inclusions such as mollusk shells and 

 rock fragments. If possible, samples of each interval should be dried and 

 examined under a binocular microscope to determine the general composition 

 of constituent particles, and these data should also be entered in the log. 

 Such data are helpful in correlating lithologies between cores and in detec- 

 ting breaks in the sedimentary sequence. 



In addition to the descriptive core log, a carded log on which actual 

 samples of the core intervals are glued in correct sequence is very useful. 

 Such logs show subtle gradations of color and texture that cannot be ade- 

 quately characterized by written descriptions and provide a convenient means 

 of correlating a large number of cores. A brief description of this proce- 

 dure is presented in Appendix B. 



IV. SUMMARY 



A pneumatic vibratory coring apparatus designed to recover 20-foot cores 

 in cohesionless sediments on the seabed has been described. This basic 

 system, improved to recover cores up to 40 feet long, has been used for nearly 

 18 years by CERC to conduct geological surveys of most U.S. Inner Continental 

 Shelf areas and Lakes Michigan and Erie in order to assess offshore sand and 

 gravel resources. This experience in using the vibracore as well as handling, 

 sampling, and recording the recovered samples is presented to assist others 

 in carrying out their own programs. 



