Rock Core Barrels 

To collect the core of the rock drilled, a device known as the core barrel is used.  Core barrel retains rock core samples from drilling operations. Rock coring collects bedrock cores for engineering and geological data. A diamond bit attached to a core barrel is lowered into the hole on the end of drill rods. 

Rock core samples are obtained by removing the inner barrel assembly from the core barrel of the drill rod using an overshot retriever.