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 bits are cutting tools used to create cylindrical holes, almost always of circular cross-section. Drill bits come in many sizes and have many uses. Bits are usually connected to a mechanism, often simply referred to as a drill, which rotates them and provides torque and axial force to create the hole.
Typical Cordless Hammer Drill. A hammer drill/driver is a drill with a specialized âhammerâ mode that is used when drilling into masonry such as brick, cement, and similar materials. The hammer mode can often be turned off so that the drill can be used as an ordinary drill/driver. The hammer drill capabilities do add a little to the weight.