Core Extrusion

The method of core extrusion depends upon the type of corer used. Kajak, Glew and similar cores up to 50 cm long can be extruded on the screw-threaded extruding rig allowing sampling intervals of 1 mm if required. Mini-Mackereth and Fat Livingstone cores are extruded using the pole and pin and can therefore only be sliced at 0.5 cm intervals or coarser at the moment. The project leader is responsible for specifying the sampling intervals required for each particular core. Core slices are usually placed directly into whirlpak bags following extrusion. This has the advantage of avoiding the need to transfer dried sediment from petri dishes to bags at a later stage for storage, and also prevents the sample from losing water before wet density analysis can be done. .

The conventional Livingstone cores are extruded whole in the field and carried back in 1m lengths of split piping wrapped in cling film. These cores should be wrapped in tubes of polythene and heat-sealed if they are not to be analysed immediately.

Glew, Mackereth and "Fat" Livingstone extrusion techniques will normally be demonstrated by one of the technical staff, if asked.