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.
In the conventional rotary drilling process, a drilling bit on the lower end of a drill pipe is turned by a rotary table, boring through layers of rock at several hundred revolutions. Drill collars are used to increase the drilling pressure. Jetting liquid is used to cool the rotary drilling bit and transport the drilling material to the surface. Modern drilling rigs on the other hand work with a so-called top drive suspended by a hoist on the derrick.