Plate 109

Injection structures: mud volcanoes

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Natural gas can escape from leaking reservoirs in the subsurface or decomposing organic matter at the bottom of lakes and swamps. It can get out dry or mixed with saltwater and fine sediment. In the second case, cones of mud are built around vents. Plate 109 documents a salse,  i.e., the initial stage of cone formation, which consists in successive additions of lobes and tongues of mud made by small-scale mud flows. The wrinkles you see are "frozen" when the mud stops and dries out; another morphological characteristic of mud flow deposits is the steepness of frontal and lateral edges, due to the cohesion of the mud.

Salses of Nirano near Modena, Italy.

Glossary