An inexpensive machine has been developed to split longitudinally cores of unconsolidated sediments without extruding them from the plastic tubing in which they were collected. This machine has four main advantages: (1) minimal amount of core disturbance, (2) speed and simplicity of operation, (3) accommodation of cores of various lengths and diameters, and (4) portability. The method of operation begins by mechanically pushing a core in its liner, laid in a V-shaped trough, through a set of gas burners which are diametrically opposed in a plane vertical to the trough. This step slightly heats the plastic liner along a thin line on opposite sides of the liner. Immediately following the burners is 0.045 inch diameter piano wire strung in the same plane as the burners. After the liner emerges from the burners the soft plastic is easily cut by the piano wire and the core and liner are sliced into equal halves.