Measuring Ocean Sediment with Spectrophotometers

The first information about rocks or minerals is obtained from its color in most cases. Previously this was done by visual comparison with the Munsell Rock Color Chart, and the results were recorded as Munsell data. In the "Ocean Drilling Program", in order to study the geological history or past environment, a hole is drilled in the seabed several thousand meters below the ocean surface, and the sediments are collected from dozens of meters beneath the seabed. The color is then measured as one part of the information about the sediments. Visual evaluation on board a ship has several problems including 1) different illuminating and viewing conditions, 2) measurement error due to individual observer difference, 3) collected data is only Munsell data, for which the color space is irregular and not so quantitative. On board, the cylindrical core sample collected from the seabed is cut in half. Sections of the core sample are then measured with a Spectrophotometer which is connected to a personal computer, and the position (depth) is input as the comment.