- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
The drilling tool is designed for use with light shot-hole type drilling. It can be built inexpensively in most machine shops. The tool has the advantage over the "drill pipe method" in that entire soft and horizontally laminated cores can be oriented with no dependence on the basal piece of the core which is often not recovered. The orienting device is 20 ft. long and is heavy steel pipe. It is tipped with a 1-3/4 in. insert-type drilling bit. Around the steel pipe is a 3 ft. sleeve which is slotted at the lower end. On the sleeve is mounted a lever and arm mechanism. A small projection on the pipe fits into the slot at the lower end of the sleeve preventing relative movement of the pipe and sleeve. The orienter has worked successfully in more than 40 test holes in central Oklahoma. Oriented cores were obtained from a friable Late Pennsylvanian sandstone at depths around 250 ft.