The factor may be related to a present-day lacustrine effect, viz. coprecipitation of Ni, Co, Zn and Cu with oxides of manganese, although it would be expected that the loading of Fe would be greater in such a factor. Alternately, the factor may be related to bedrock (or till) composition; certainly, the zone of high scores includes the mapped Bravo Lake mafic volcanic belt but the mapped outcrop of the latter unit is insufficient to account for the entire extent of the former. A third is the interaction of these two agencies (coprecipitation and bedrock composition) which the factor analysis is unable to separate.
As with Factor 3, scores do not display a significant correlation with sample depth or lake area, although the scores for samples recorded as being black, or some combination of black with some other colour, seem to be slightly lower than for other colours (see box plots).