Rock core

A rock core is a special type of drill core and is a long tube looking run of rock obtained from the subsurface by drilling using a drilling rig. Usually using a method called mud rotary and cutting with a 2 inch bit and can be a few feet in length to hundreds of feet in length.

Rock cores are drilled for many reasons. Geotechnical engineers and geologists will obtain rock cores in order to test a rock units suitability for building upon, either for building structures or to add fill material. Rock cores are often drilled in order to assess environmental impact of a contamination plume. Even state geological surveys will drill them for scientific research. Rock cores are even drilled offshore for the previously mentioned reasons.

Figure 1: This is a rock core obtained from Ripon, Wisconsin. The numbers in the picture represent the depth of the core in feet below the surface. The box that it is in holds 10 feet of core. In this case the top is upper right of the box and the bottom of the run is lower left.

Figure 2:

This is the geological interpretation of the rock core in figure 1.

References

*2006: "Steven Baumann", Core Log RI-3001
*1984: "R.L. Bates & J.A. Jackson", Dictionary of Geological Terms, 3rd Edition