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.
while the term drill may refer to either a drilling machine or a drill bit for use in a drilling machine in this article for clarity drill bit or bit is used throughout to refer to a bit for use in a drilling machine and drill refers always to a drilling machine