Wegener also noted that the continents move up and down to maintain equilibrium in a process called isostasy. As an example he cited the sinking of Northern Hemisphere lands under the weight of continental ice sheets in the last ice age, and their rise since the ice melted some 10,000 years ago.
Drill that is fitted with a Pipe provides effective connection to the rig surface equipment or application with the bit and the bottom hole assembly for the purpose of pumping the Drill fluid to the bit.
drill bit upper left mounted on a pistol grip corded drill drill bits are cutting tools used to remove material to create holes almost always of circular cross section drill bits come in many sizes and shape and can create different kinds of holes in many different materials in order to create holes drill bits are attached to a drill which powers them to cut through the workpiece typically by rotation the drill will grasp the upper end of a bit called the shank in the chuck