Figure 1
From: Natural glass alteration under a hyperalkaline condition for about 4000 years
Outcrop photographs of the ultramafic clastic sediment containing a volcanic ash layer: (a) Overhead shot photograph of a trench where the crosses denote sampling points. (b,c) Cross-section of the trench. Solid samples were collected at different depth indicated by small flags. The numbers in parentheses are the 14C ages of humin extracted from the clastic sediments (years before present).
