The area around Tillei and McPherson lakes includes extensive exposure of a relatively thick, late Neoproterozoic limestone. The limestone is lithologically similar to the Espee Formation of the Ingenika Group, but is in geological continuity with the Hyland Group. The Hyland and Ingenika groups are age-equivalent sequences that were in close proximity before they were separated by Cenozoic dextral displacement on the Tintina fault. The area may therefore contain evidence for stratigraphic linkages between the two groups. The limestone is interpreted to have been deposited in a high-standing region outboard of the Hyland Group type-area. Further work is required to determine the extent to which late Neoproterozoic paleobathymetry aligns with Paleozoic platform/basin margins.