The hole is advanced by turning sections of auger casing, called auger flights, into the subsurface. Rotating of the auger flights carries the soil to the surface. This method is most effective when used in stable soil conditions which are generally free from cobbles and boulders. The advantages of this method are that the hole is drilled and cased simultaneously, and the hole can be advanced without the introduction of fluids. Some of the disadvantages are that drilling difficulty significantly increases with depth and the auger flights must be removed from the hole without rotating to avoid damaging the installed instrument.