FIGURE 5. A microscope image of a gas hydrate (or clathrate) structure found in Lake Vostok's accreted ice 3,566 m below the ice-sheet surface, which is 174 m above the lake surface.
From the following article:
Physical, chemical and biological processes in Lake Vostok and other Antarctic subglacial lakes
Martin J. Siegert, J. Cynan Ellis-Evans, Martyn Tranter, Christoph Mayer, Jean-Robert Petit, Andrey Salamatin and John C. Priscu
Nature 414, 603-609(6 December 2001)
doi:10.1038/414603a
Fifteen similar clathrate structures, between 3 and 5 mm in diameter, were identified within a 32-cm-long vertical section of the accreted ice. This structure is formed as the ice relaxes under normal atmospheric pressure, causing the hydrate to convert to gas and expand.
