The pre-Kenoran Archean stratigraphy has always been of prime interest to geologists working in the Superior Province. However, one must realize that the problems raised have remained, for the most part, without satisfactory solution. Thus, the respective age relation of the thick lithostratigraphic metavolcanic and metasedimentary units (Pontiac), forming respectively the Baby Rift and its northern flank to the northeast of Ville-Marie in Temiscaming, has not been defined with certainty to date.During a geological mapping project on a scale of 1:12 000, covering the township of Baby and adjacent parts of the townships of Guérin and Guigues, it has become possible for us to remove the uncertainty and to define the age relation of the two units mentioned. We can now state that the metasedimentary unit (Pontiac) forms the stratigraphic base of the metavolcanic unit.To arrive at this conclusion it was first necessary to determine the size of the main folded structures in the region of Rapide des Quinze, then to uncover and let weather the outcrops over several kilometers, in order to define the actual contact of the two units. [Translated by the Journal]