Buffalo Head Hills kimberlite field grained, and well bedded, with high bedding angles. The reworked kimberlite is well sorted, distinctly bedded, and contains abraded olivine grains. Multiple layers of pyroclastic and reworked kimberlite separated by layers of marine mudstone are present at some pipes. These represent a series of discrete kimberlite eruption events separated by quiescent periods during which the muds were deposited. The majority of the BHH kimberlites are diamondiferous, in contrast to those of the Birch Mountains kimberlite field to the northeast which are mostly barren of diamonds. Based on petrography and whole-rock geochemistry, the BHH pipes are classed as Group 1A kimberlites.
Buffalo Head Hills kimberlite field in mudstones that are interbedded with some of the kimberlite deposits are consistent with the Late Cretaceous age. The BHH kimberlite pipes cover areas ranging from one to . They represent maar-style volcanoes which have a vertical-walled volcanic crater of explosive origin, surrounded by a low rim of ejecta and filled with water. Pyroclastic fall and surge are the two volcanic mechanisms of deposition. There are also deposits formed by hydraulic reworking of kimberlite from tephra cones and/or extra-crater fall and surge deposits. The pyroclastic fall deposits are poorly sorted and massive, while the surge deposits are better sorted, fine