posed to cores, which have to be hauled to the surface between active-drilling times. When cuttings arrive at the surface, they are collected either with the surrounding drilling mud or screened out of the drilling mud and saved for later laboratory processing. Cuttings washed free of drilling mud are dried and stored in small (about 2- by 3-inch) envelopes, categorized by the depth from which they were gathered.
Although comparatively cheap and quick, cuttings still yield important information about the character and age of the rock penetrated during drilling. The use of cuttings has been somewhat limited (compared with cores), however, because of their tendency to mix with adjacent cuttings during their trip from the drill bit to the surface and because of their small size (individual cuttings typically are 1/4 inch and smaller). Mixing somewhat diminishes the ability to pick precise depths of important rock units or other features of interest. The small size of individual cuttings hides recognition of some larger important features (especially fractures). Sidebar 1-6 describes new techniques being developed to extract additional information from fluid inclusions found in cuttings.
Several major non-industry projects generate significant amounts of core for basic scientific exploration of Earth’s crust or ice sheets. These scientific drilling programs include the Ocean Drilling Project (ODP), Drilling, Observation, and Sampling of the Earth’s Continental Crust (DOSECC, 1998), Antarctic (WAIS, 2000) and Greenland (ARCSS, 2002) ice-coring projects. The ODP and ice-coring projects serve as excellent examples of research communities that understand the importance of hard-won core and plan for adequate access and maintenance (see chapter 4).
Rock cores and cuttings are held by petroleum companies, other natural-resource companies, the USGS, state agencies, individual researchers at colleges or universities,