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.
Can be used to drill out broken bolts, studs, taps and drill bits. They also cut hard steel such as safes, bearing races and dies. The carbide is designed to prevent chipping and dissipate heat quickly. These drills are designed solely for use in hardened steel and perform poorly in softer materials.