(con't)
Unconsolidated or moderately consolidated sub-bottom samples can often be collected by vibracoring. However, harder bottoms frequently require the use of percussive (hammer) or rotary drilling techniques. During standard drilling, a casing is either hammered or screwed into the bottom to project sampling depth.
A split spoon is pushed into the casing and immediately removed to collect samples at prescribed depths. Split spoon samples are typically removed from the spoon and containerized.

Unlike a split spoon, a Shelby tube is inserted and then pushed into the casing pipe. Then the sample is allowed to swell in the tube for up to 30 minutes to prevent loss during extraction. After the removal the sample tube is capped and wax sealed for offsite testing..