Читать книгу Reconstructing Earth's Climate History - Kristen St. John - Страница 17

Coring allows scientists to access the record of a sequence of climatic and environmental conditions (i.e. a history) locked away in natural archives. Trees, corals, sediments, rock, and ice are all cored for paleoclimatic studies. Cores are narrow, cylindrical samples that extend through layer after layer of the material being investigated. Tree cores are thinnest, only ~0.5 cm diameter and <50 cm long. Coral, sediment, rock, and ice cores are often a few centimeters in diameter and of variable length (<50 cm to 10 m in length), depending on the coring technology used, the thickness of the material being cored, and the objectives of the study. Repeated drilling in the same hole can recover many successive meters of core from successively greater depths (Figure 1.5). The deepest cored hole in glacial ice (EPICA Dome C) is over 3.2 km deep and is located on the high Polar Plateau in East Antarctica. The deepest cored hole in the seafloor is over 3.2 km deep and is located in the Nankai Trough in the Pacific Ocean near Japan.

In this exercise, you will investigate how cores are obtained from a set of terrestrial and marine paleoclimate archives. The fieldwork takes scientists to places near and far, and the approaches they use are purposeful and innovative. You will also explore issues common to all types of paleoclimate research, including the need for teamwork, for methods that keep samples uncontaminated and organized, for reproducible results, and for funding.

FIGURE 1.5. Example of (left) an ice core from Huascaran, Peru, and (right) a sediment core from the western equatorial Pacific Ocean.

(Source: photo credits: ice core – Lonnie Thompson, http://researchnews.osu.edu/archive/lonthmppics.htm; sediment core – Mark Leckie).