This diagram shows a cross-section of the path of rainwater down into a cave system. Rainwater picks up impurities from the soil and rocks and leaves them behind in cave formations. These impurities can be used as signals of surface climate and ecosystem change.
Adapted with author permission from: Blyth, A. J., Hartland, A., & Baker, A. (2016). Organic proxies in speleothems – New developments, advantages and limitations. Quaternary Science Reviews, 149, 1–17. https://doi.org/10.1016/j.quascirev.2016.07.001