Comparison of annual luminescent and visible laminae in stalagmites

Polished sections of stalagmites from France and Belgium were examined using UV excitation and natural light in order to examine their annual growth laminae. The most prominent luminescence occurs in the dark compact laminae; this would signify that both types form at the end of Autumn or the beginning of Winter when soil organic matter is flushed into the cave. Under UV excitation, and at a weaker magnification, white porous calcite fabric is found to be much more luminescent than the dark compact one. These results could be due either to optical effects associated with porosity or to the higher luminescence of dark compact laminae.