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.
What is the primary purpose of drill (drill and ceremony)? The purpose of drill is to enable a commander or non-commissioned officer to move his unit from one place to another in an orderly manner; to aid in disciplinary training by instilling habits of precision and response to the leader's orders;and to provide for the development of all soldiers in the practice of commanding troops.