Lower Viséan (upper middle Osagean) ammonoids from microbial carbonate mud mounds in the lower
 member of the Mount Head Formation in the Monkman Pass map area of east-central British Columbia,
 include Merocanites rileyi n. sp., Imitoceras tardum n. sp., Irinoceras bamberi n. sp., Goniocycloides
 ochakensis n. gen. et sp.,  Polaricyclus canadensis n. sp., Eurites kusinae n. sp., Dzhaprakoceras belcourtense
 n. sp., D. crassum n. sp. and Furnishoceras heterolobatum n. gen. et sp.  The ammonoids generally resemble
 faunas from the Fascipericyclus-Ammonellipsites Zone, particularly those from the Tournaisian-Viséan
 boundary beds in the Chadian of the United Kingdom.  To some extent however, the age of  the ammonoid
 beds in British Columbia is refined or constrained by other associated faunal groups.  The ammonoids are
 directly associated with upper Scaliognathus anchoralis-Doliognathus latus Zone conodonts that indicate
 correlation with the upper part of the middle Osagean Burlington Formation in the Mississippi Valley.
 Further, the ammonoid beds are underlain and overlain by strata containing representatives of the definitive
 Viséan foraminifer Eoparastaffella with a subangular to angular outer periphery - that is, morphotype 2.

    The lower member, a coeval correlative of the Wileman Member of the Mount Head Formation of
 southwestern Alberta, was deposited on the northwest-trending Sukunka Uplift, of block-fault origin.
 Recessive carbonates and siliciclastics of the lower member generally overlie the upper Tournaisian to lower
 Viséan Tumer Valley Formation conformably, and are abruptly overlain by the lower Viséan Baril Member
 of the Mount Head Formation.

    The microbial carbonate mounds occur as isolated deposits between 2 and 8 m thick and as complexes of
 small buildups developed in shallow-neritic settings.  Enclosing facies in the lower member are of peritidal-
 marsh to neritic-shelf origin.