Global Volcanism Program | Image GVP-06085
Icelandic volcanologist Sigurdur Thorarinsson (right center, with red cap) discusses ash layers exposed in an excavated pit with an international group of volcanologists on a field trip. Thorarinsson pioneered the technique of tephrochronology, and his detailed studies of tephra layers from Hekla demonstrated the value in determining the relative ages of ash layers by their stratigraphic position between dated horizons.
Photo by Bill Rose, 1980 (Michigan Technological University).
This image is made available under the Creative Commons BY-NC-ND 4.0 license terms.