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.
Construction drill auger. Wood augers have a screw to pull them into the wood, as a gimlet has, and a cutting lip that slices out the bottom of the hole. The auger bit, meant to be used in a brace, also has cutting spurs to cut a clean circle deeper than where the lips scrape out the wood. In construction, augers are used for special drilling rigs to dig holes, or augerating for deep foundation piles. Another use is for piles forming a piling retaining wall, which can be constructed in the same way as foundation piles. Augers â either gas- or hand-powered â are used by ice fishermen to drill holes to