The Heritage Group is composed of about 7,500 m of sedimentary strata exposed in the Heritage Range of the Ellsworth Mountains, West Antarctica. The Heritage Group is here redefined to include the Minaret Formation as the uppermost unit. New formations within the Heritage Group are formally described; they are, from the bottom upward, the Union Glacier, Hyde Glacier, Drake Icefall, Conglomerate Ridge, Springer Peak, Liberty Hills, and Frazier Ridge Formations. The Kosco Peak Member of the Union Glacier Formation is also formally described. Deposition of the Heritage Group took place in Middle and early Late Cambrian time in a rapidly subsiding basin bordered by carbonate rock and quartzite source areas of moderate relief. Sediment transport directions were dominantly from the present south and west. Thick, volcaniclastic terrestrial strata lie at the exposed base of the group, and these rocks grade upward into deltaic black shale and normal marine sediments. A number of active volcanic centers were present in the Heritage Range during the deposition of upper Heritage Group strata.

Carbonate rocks were studied from the Middle Cambrian Drake Icefall Formation and the Middle to Upper Cambrian Minaret Formation. Additionally, carbonate clasts from the Middle Cambrian Union Glacier Formation and the Permo-Carboniferous Whiteout Conglomerate were examined. No in situ Lower Cambrian carbonate rocks are known to crop out in the Ellsworth Mountains; only reworked clasts of such rocks are found in the Heritage Group and the Whiteout Conglomerate. These clasts suggest that during Early (and Middle?) Cambrian time, a wide carbonate platform developed in or close to the Ellsworth Mountains. This was the site of skeletal algae and archaeocyathid boundstones with sparry calcite or mud as matrix—typical sediments of an open marine environment with low to medium hydrodynamic energy. Oolites are common, and a high-energy environment was required to form these oosparites. These grains, with a diameter between 4 and 7 mm, are made up of concentric ooids with simple and complex structures. Nuclei consist of abraded ooids and oolitic intraclasts. Half-moon ooids with collapsed internal structure are attributed to partial solution, and they indicate a hypersaline depositional environment (aragonite or calcium sulfate?) for some parts of the oolitic bank facies. Laminites with fenestral structures are also present, and they represent low-energy lagoonal deposits. These occur along with dome-shaped and LLH stromatolites that indicate an intertidal environment. Some areas of the carbonate platform were elevated and partly dissolved by fresh water. During the following period of subsidence, voids were filled with fibrous carbonates by rhythmic cementation. Renewed uplift resulted in erosion and destruction of the carbonate platform. The lowest in situ marly and oolitic carbonates are found in the Middle Cambrian strata of the Heritage Group north of Drake Icefall, but these were not extensively studied. The Upper Cambrian Minaret Formation is also autochthonous, and its thickness increases southward from 8 m in the northern Webers Peaks to several hundred meters in the Marble Hills area. Medium to high hydrodynamic energy conditions prevailed during deposition of the Springer Peak section of the Minaret Formation (biosparite, oncosparite, pelsparite). The high diversity of the fauna indicates an open marine environment. The section at Yochelson Ridge starts with a few meters of still-water carbonate rocks that are overlain by high-energy oolitic carbonate rocks and calcarenites. Farther to the south (south of Mount Dolence), facies fluctuate from medium-energy (oncolite) to high-energy (oolite) environments. Fossils (brachiopods and trilobites) are rare. Near the top of the sequence a hypersaline milieu is indicated by layers of early diagenetic dolomicrite. Similar fades are exposed in the Liberty and Marble Hills areas. Fast subsidence in this area was compensated by rapid sedimentation of shallow-water carbonates.

Cambrian rocks of the Springer Peak and Minaret formations of the upper Heritage Group contain conodont faunas. The upper Middle Cambrian Springer Peak Formation has yielded a conodont cluster referable to Phakelodus , and the Upper Cambrian Minaret Formation has yielded conodonts of the genera Furnishina , Proacodus, Phakelodus , and Westergaardodina . Three species each of Furnishina and Westergaardodina are known worldwide; other specimens of Westergaardodina may represent new species, but low numbers and generally poor preservation preclude reliable diagnosis. All of the identified paraconodont and protoconodont taxa are long ranging, but they are consistent with the Cambrian age of the host rocks as determined by the other contained fossils.