What is a Core Sample?

Mary McMahon
Mary McMahon

A core sample is a specimen of mud, soil, rock, or similar material taken in the form of a cylindrical block, preserving the arrangement of its contents. It provides an opportunity to look inside geological formations, the ocean floor, and other environments. The preservation of a solid block shows researchers the distribution of materials inside the formation and can highlight features like a thin layer of different material sandwiched between larger layers. Core samples are useful for mineral exploration, scientific research, geology, and oceanography.

A core sample provides an opportunity to look inside geological formations, like the ocean floor.
A core sample provides an opportunity to look inside geological formations, like the ocean floor.

Several techniques are available to take a core sample. The goal is to lift out a complete chunk of the material under examination, keeping it as intact as possible. One simple method is to drop a metal cylinder, using gravity to drive the cylinder into the material, and grab a core sample. Other core samples require drilling because of the hardness of the material under investigation. As researchers take the sample, they note the circumstances, including the exact location, date and time, and name of the researcher taking the sample.

Core samples may be analyzed under a microscope.
Core samples may be analyzed under a microscope.

The core sample must be accompanied by documentation providing context. This includes notes to indicate which way is up, as this can be important; if a mud sample ends up upside-down, for example, scientists might draw erroneous conclusions on the basis of bad information. It is also important to have a precise location for the sample, especially when scientists take multiple samples in a survey of a given area. If samples get mixed up, it can result in data errors.

For geological exploration, core samples are extremely useful. Before investing in setting up oil wells or exploring for materials like precious stones and metals, companies want to know if a site will be productive. They can use a variety of techniques to collect data about the location. Core samples are often very informative, indicating whether materials of interest are present, and providing information about their concentrations.

Several scientific institutions maintain libraries of core samples, including ice samples, samples from trees, and so forth. These can be very useful references. Researchers may use them to compare and contrast the characteristics of various materials. Storage facilities have excellent climate control and inventory management systems to make sure samples stay in good condition while preventing sample mix-ups. They may also have investigational facilities to allow researchers to take images, withdraw sections of a core sample for investigation under microscopes, and engage in other activities.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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