A cylindrical rock-drilling tool, designed to cut an annular space around a central cylindrical core of rock, which can then be removed to classify the material or in the case of a drilled shaft removed to deepen the hole.
A vertical section of reservoir or other rock taken in drilling a well, for detailed study and analysis. In order to retrieve the core as intact as possible, it is cut from the rock by an annular core bit. The central column of rock passes through the centre of the bit and, as the bit cuts deeper, is received by a hollow cylindrical Core Barrel above the bit, where it is retained and protected by a series of rubber baffles. When the bit has cut deep enough to fill the core barrel, it is withdrawn from the hole and the core extracted. In this way the actual sequence of rock strata is preserved.