A section of Permo-Carboniferous rocks located near the headwaters of Thornton Creek in northern Jasper National Park was examined to reconstruct the conditions of sedimentation, and to investigate the diagenesis and alteration of these rocks. Depositional environments were interpreted from textural, mineralogic, and faunal information.

Mississippian sedimentation was cyclic, the sediments reflecting shallow-water shoal, intershoal, bank, and lagoonal environments. Uppermost Banff Formation ediments are alternating shallow-water limestones and dolostones formed in restricted environments. A shoal area with periodic restriction of the waters marked Pekisko time in the Jasper area. Shunda Formation sediments contain much ooze; the area during this time was probably very similar to the protected shelf lagoons existing on the Bahama Banks today. Turner Valley and Mount Head Formations are highly dolomitized.

Permian sedimentation began with the deposition of a basal conglomerate over an erosion surface, after which the sediments consist of a shallow-water deposit of spicular chert overlain by a quartzose sandstone, which possibly indicates a regressing sea.

Dolomization probably took place at an early diagenetic stage, and may have been caused by magnesium-rich solutions resulting from evaporitic concentration of normal sea water in restricted environments.

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