The A4 pipe, also known as the Alfie Creek 1 pipe, intruded Archean intermediate to basic volcanic and Paleozoic carbonate rocks approximately 156 Ma ago and consists of tuffaceous kimberlite breccia. The subcropping surface is 200 m wide by 400 m long. A smaller kimberlite pipe is 300 m to the southwest. Glacial sediments are thickest (25 m) directly over the pipe and consist of 1 to 3 m of silty sand till at the base overlain by 10 to 20 m of interbedded sand and sandy till, which is in turn overlain by 25 m of glaciolacustrine silty sand. Till overlying the south end of the pipe is dark green and contains abundant kimberlite clasts and indicator minerals. The relative abundance of indicator minerals in the A4 kimberlite is: pyrope >Cr- diopside > chromite > Mg ilmenite. The A4 property is the best example of a till geochemical signature reflecting kimberlite dispersal. Till overlying and down-ice (south) of the kimberlite is enriched in Ba, Ca, Co, Cr, Cu, Mg, Ni, Sr, Ti (<0.063 mm fraction) and Ba, Cr, Ni, Ta, La, Eu (heavy mineral fraction). Samples of geochemically anomalous till contain 100's of indicator minerals.