FIG 1.

Downcore permafrost borehole characteristics. (A) Photos of Yedoma and Olyor sediments and their relative depths, with triangles indicating depths that produced MAGs and filled triangles indicating depths with MAGs that were >80% complete and <10% contaminated. Concentrations of major ions are shown for each depth. Note that the depth intervals are discrete in panel B to spread the data points evenly across the depths. (B) Concentrations of methane for each depth. Other geochemical measurements, including temperature, pH, and total carbon, are available in Fig. S1 in the supplemental material. The small dashed line at 7.7 m shows the depth of the transition between the Yedoma and Olyor layers.