2. Coring Performance . 



In the nearly 18 years that CERC has been using vibracorers for the ICONS 

 program, more than 1,600 cores have been collected and analyzed. That experi- 

 ence has shown that penetration rates, depths, and sediment recovery can vary 

 greatly depending on what coring equipment is used and, especially, on the 

 physical nature of the sediment being cored. The easiest penetrations and 

 best recoveries are made in soft, cohesive material such as lacustrine or 

 estuarine sediments. Medium and coarse grain-sized sand and gravels also 

 offer little resistance and recoveries are generally 75 to 100 percent; how- 

 ever, there is less success in coring firm and overconsolidated clays, glacial 

 tills, and gravels with little or no sand. Some cores which have recovered 

 shale bedrock and semiconsolidated Coastal Plain sediments are generally less 

 than 0.6 to 0.7 foot (15 to 20 centimeters) in length and their hardness can 

 blunt the edge on the cutterhead. 



III. RECORDKEEPING AND CORE PROCESSING 



1. Core Record . 



The identity, location, water depth, and other pertinent information for 

 each core should be maintained in a suitable, ruled looseleaf or bound record 

 book aboard the coring vessel. A separate page is used for each core with the 

 cores numbered in sequence from the start of the survey to the end. Entries 

 for each core should include project name, core number, navigation fix loca- 

 tion, date and time taken, water depth, vibration time, penetration depth, 

 actual recovery, and a description of the sediment characteristics at the top 

 and bottom of the core as well as any sediment that might be brought up on 

 the core-rig legs. It is recommended that the logbook either be reproduced 

 or a duplicate log maintained to avoid loss or damage to the original logbook 

 because of the extreme importance of the logged information to future usability 

 of the cores. 



2. Core Handling and Marking . 



After the coring apparatus is placed onboard the vessel, the core liner 

 is removed and reference samples from top and bottom are bagged and labeled . 

 Core recovery should then be measured and recorded. After the liner is cut 

 into lengths for easier handling and the unfilled ends are removed, the ends 

 are sealed with tightly fitting plastic caps and duct tape. The core is then 

 carefully moved to a storage area to minimize postcoring disturbance. 



To avoid errors in identifying cores, it is essential that the core liners 

 be carefully labeled immediately after recovery. Each core label should con- 

 tain an identifying serial number, with the bottom and top clearly marked, the 

 date the core was taken, and the project area. If the core is sectioned into 

 shorter lengths to facilitate handling and storage, each section should con- 

 tain the above basic information plus section numbers or letters from the top 

 to the bottom with arrows pointing to the top of each section. In addition 

 to the essential information, the core liner should also have the core serial 

 number and the top or bottom repeated on the end caps both as added security 

 and to provide a means of identification when cores are stacked in core racks. 



