Core drilling

A drill core is a piece of rock from the bottom that is brought above water by drilling a hole in the ground. Core types may depend on the drilling system. Cores can be taken from both bedrock and unconsolidated sediment.

Drill core
A drill core is taken by a special drill bit, with a hollow core. The chisel drills a cylindrical piece of rock and the drill core is being held in the hollow chisel. Then the piece of rock is gently removed. A typical length of a drill core during research bores in unconsolidated sediments is normally 1 to 2 meters. To obtain longer cores, different cores must be taken sequentially. In order to despose of drill cuttings, a drilling fluid must continuously be circulated in the borehole. The drilling is slow and the process is a precision job. Especially in harder rock types it may take a very long time to drill a core.