carottage

Carottage is the process of obtaining a cylindrical sample, or core, from a material such as soil, sediment, rock, ice, or subaqueous deposits using a hollow drill and a core barrel. The goal is to recover an intact, stratigraphically representative column that can be analyzed with minimal disturbance to the surrounding material. This distinguishes coring from ordinary drilling, which primarily aims to create a borehole rather than preserve a core.

Coring uses a variety of equipment depending on the substrate. Piston and push corers are commonly employed for soft to semi-solid sediments, while vibrocorers are used for moderately consolidated layers. For solid rock, diamond-tipped core bits and deep-core drilling rigs produce rock cores within a steel or composite core barrel. Ice cores are obtained with specialized ice-core drills designed to preserve isotopic and layering information. In marine or lacustrine settings, gravity or specialized coring systems mounted on vessels or platforms are used to collect sediments from the bottom.

Applications of carottage are widespread. In geology and paleoclimatology, cores provide stratigraphic sequences, fossil content, and proxies for past environmental conditions. In hydrology and petroleum geology, cores support mineralogical, porosity, permeability, and reservoir studies. Archaeology and paleoanthropology use sediment or peat cores to investigate past human activity and environmental context. Cores are analyzed for physical properties, chemical composition, microfossils, isotopes, and contaminants, with dating techniques such as radiocarbon, paleomagnetic analysis, or other radiometric methods.

Quality and limitations include core recovery rate, potential disturbance or compaction, core breakage, contamination during handling, and the need to select an appropriate coring method for the substrate. Proper storage, labeling, and documentation are essential for reliable interpretation.