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.
a removable drilling or boring tool for use in a brace, drill press, or the like. a removable boring head used on certain kinds of drills, as a rock drill. a device for drilling oil wells or the like, consisting of a horizontally rotating blade or an assembly of rotating toothed wheels.