The North French Watershed, located on the traditional lands of the Moose Cree First Nation, contains culturally and ecologically important forested peatlands on the Boreal Shield. Peat soils are a significant existing carbon pool that contribute to the annual carbon sink. However, modelled soil carbon estimates lack certainty due to ground data gaps in terms of overall carbon stocks, peat depths and organic matter (OM) quality/stability, which impacts predictions for future carbon balances and has important implications for Canada’s commitments to net zero emissions by 2050. In 2023 we collected a peat core (3.8m) from a treed bog, adjancent to Bounce Lake, within the North French River watershed. We used Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (FTIR-ATR) alongside other soil parameters (bulk density and loss-on-ignition) to characterize changes in OM quality with depth. Using FTIR-ATR analysis of selected IR ratios and changes in peak intensities with depth we determined quality of OM. With depth, we saw depletion of labile OM and an increase in recalcitrant OM. Using a series of wave numbers associated with degree of peat humification, we recorded a sharp increase in humification with depth 215 cm below surface. The peat contained woody, undecomposed layers at differing depths throughout and patterns of lignin decomposition were varied. Our analyses show complex patterns of organic matter quality down core, showing that a better understanding of peat composition with depth is critical when determining the stability of these systems as carbon sinks in the face of climate change.