A series of small mud mounds are exposed in the McConnell and Miette thrust sheets on the southern flank of the Miette reef complex. They occur on the southeastward inclined carbonate clinoforms of the late Frasnian Arcs Member. These mounds are rooted on marine, argillaceous lime mudstones and are surrounded by lime mudstones of several prograding clinoforms of the upper Arcs Member or dolomitic siltstones of the lower Ronde Member.

Mounds are approximately 17 to 36 m high and 32 to 81 m wide and columnar to domal in shape. The lower part of the mounds consists of sponge-rich wackestones and packstones, and locally laminar stromatoporoid boundstones. Calcareous green algae tend to predominate in the upper parts of the mounds.

Variable cavities occur and are filled with geopetal sediments, isopachous fibrous and blocky calcite cements. The most common cavity types, irregular and irregular stromatactoidal cavities, might be related to organic origins, possibly the decay of sponges in conjunction with submarine cementation.

Abrupt mound margins indicate that the mounds grew upwards more rapidly than the accumulation of the adjacent basin and clinoforming slope sediments. (Abstract shortened by UMI.)