The Crashsite Group of the Ellsworth Mountains, a 3,000-m-thick sequence of shallow-water, mostly marine, tan, green, and red quartzose sandstones (quartzites) and argillites, is here subdivided, in ascending order, into the Howard Nunataks Formation (1,630 m), the Mount Liptak Formation 1,070 m), and the Mount Wyatt Earp Formation (300 m). The Mount Wyatt Earp Formation has yielded Devonian fossils. Late Cambrian trilobites occur in the transition beds at the base of the Crashsite Group, and it is probable that the lower parts of the Group include Ordovician and Silurian strata.

The upper Paleozoic Whiteout Conglomerate, situated conformably upon the Crashsite Group and overlain conformably by the Polarstar Formation, may represent the entire period of Gondwanaland glaciation in West Antarctica. The formation, mainly massive diamictites, makes up about 1,000 m of a 13,000-m-thick total stratigraphic column in the Ellsworth Mountains. In the northern Sentinel Range, the Whiteout Conglomerate contains as many as six dark gray to black, thick, massive-bedded diamictites that are separated by recessive layers of laminated to thin-bedded shale, mudstone, and sandstone as thick as 15 m. Clasts greater than 5 mm in diameter compose 3 to 10 percent of most diamictites. Quartzite (66 percent) is the dominant clast type, with granite (17 percent), shale-argillite (8 percent), and carbonate (5 percent) composing most of the remainder. Some clasts are faceted and striated. A truncated Whiteout section of about 250 m in the Meyer Hills to the south contains thinner diamictites with more variable rock types and a stratigraphic sequence punctuated by striated boulder pavements and thin laminated beds of shale, sandstone, and pebble lags. Of the pebbles in the diamictites, 47 to 86 percent are quartzites. Limestone and granite each compose about 20 percent. Conspicuous changes in pebble compositions occur across contacts marked by boulder pavements. Petrographically, the diamictites are 62 percent silt and clay matrix with 38 percent sand grains and granules. The sand-sized grains have an average quartz/feldspar/lithic (Q:F:L:) ratio of 75:9:16; the studied specimens displayed no significant petrographic variations between the northern Sentinel Range and the Meyer Hills. However, there is a difference in megaclast compositions; in the northern Sentinel Range, shale-argillite and vein quartz are abundant, but they are absent in the Meyer Hills where carbonate is abundant. Till pellets, products of ablation on glaciers and icebergs, are common in bedded units and rare in the diamictites. The Crashsite Group quartzite and Whiteout Conglomerate are dominated by quartz and quartz-rich lithic fragments, whereas the overlying Polarstar Formation contains abundant volcanogenic detritus, reflecting a dramatic change in source area. Contact zones with both enclosing formations contain scattered oversized clasts. Striated boulder pavements in the Meyer Hills generally indicate paleo-ice flow to the present northwest. With the Ellsworth block restored to its probable late Paleozoic position via a 90° clockwise rotation, the glacier source area was the East Antarctica landmass now situated south of the Ellsworth Mountains. Sedimentologic similarities with formations in the Pensacola Mountains to the south indicate that the Ellsworth Mountains have moved northward at least 500 km from a hypothetical former position just east of the Pensacolas. Our glacial model suggests that ice sheets generated the glacial sediments of the Whiteout Conglomerate under a polar climatic regime. The Meyer Hills sequence represents deposition directly by glaciers and also by floating ice and currents in a zone of fluctuating grounding line. Deeper water and sub-ice shelf conditions, i.e., glacial-marine, are postulated for the thick sequence of the northern Sentinel Range. There, periodic retreat of the ice shelf margin was accompanied by iceberg rafting and bottom current activity, probably in response to climatic warming.

The 5,500+-m Paleozoic succession of the Sentinel Range includes the Heritage Group (Cambrian), the Crashsite Group (Cambrian and younger, including Devonian), the Whiteout Conglomerate (Carboniferous?), and the Polarstar Formation (Permian). All these predominantly clastic rocks were strongly folded during the early Mesozoic (?) Ellsworth (Gondwanide) Orogeny, and the folds formed mainly by a flexural-slip mechanism. Axial planar cleavage is abundant throughout the range; it may be a solution cleavage in the massive diamictite beds of the Whiteout Conglomerate. One major, eastward-dipping reverse (?) fault cuts Crashsite quartzite beds along the west side of range. The Sentinel Range succession was subjected to mild burial metamorphism, and later dynamothermal metamorphism reached lower greenschist facies. The folds in the range plunge gently northward, and the entire Sentinel Range block may be slightly tilted eastward. Stratigraphic similarities with rocks of the Transantarctic Mountains make it likely that the Ellsworth Mountains have moved and rotated away from the margin of East Antarctica, but the sense of such a rotation cannot be determined at present. In addition, similarities exist between the Sentinel Range younger rocks and those in the Cape Fold Belt of southern Africa, as foretold by Du Toit (1937), but the Cambrian System of the Sentinel Range lacks a definite counterpart in Africa.

An Early Devonian orbiculoid brachiopod fauna was reported by Boucot and others (1967) from the Crashsite Quartzite of the northern Heritage Range of the Ellsworth Mountains. Re-collection on this site from strata now known as Mt. Wyatt Earp Formation of the Crashsite Group (Spörli, this volume) has yielded a diverse but sparse and poorly preserved fauna dominated by orbiculoid brachiopods ( Orbiculoidea cf. falklandensis Rowell). Also present in the fauna are cephalopods (identifiable only to the order Orthocerida), pelecypods ( Nuculites aff. N. cuneiformis Conrad; and Grammysiodea? sp. indt.), a rostroconch ( Hippocardia? sp. indt.), gastropods ( Holopea? sp. indt.), a fish spine ( Machaeracanthus cf. kayseri Kegel), and single unidentifiable specimens of a conularid, a trilobite, and an articulate brachiopod. The fauna correlates with those of the Lower Devonian Horlick Formation, Ohio Range, Horlick Mountains, Antarctica, and with those of the Lower Devonian of the Falkland Islands and represents the Malvinokaffric Faunal Province.

The stratigraphic succession in the Ellsworth Mountains includes strata from Cambrian to Permian in age. No definite evidence of major unconformities in the Ellsworth succession is known, and it is possible that continuous deposition took place from Cambrian to Permian time. The oldest stratigraphic unit, the Heritage Group, was deposited in Middle to Late Cambrian time. More than half of the 13,000+-m-thick stratigraphic succession of the Ellsworth Mountains was deposited during this time interval. Basic igneous volcanism and tectonic activity occurred in both the source and accumulation areas throughout the deposition of this group. Shallow-marine conditions prevailed during the deposition of the overlying 3,000-m-thick Upper Cambrian to Devonian Crashsite Group. This group indicates a period of tectonic stability that continued through the remainder of Ellsworth Mountains sedimentation. Deposition of the glaciomarine Permo-Carboniferous Whiteout Conglomerate and the Permian Polarstar Formation completed the sedimentary sequence. Major deformation of the Ellsworth Mountains sedimentary succession, the Ellsworth (Gondwanide) Orogeny, took place in Late Permian or early Mesozoic time. The original location of these rocks is unclear, but they probably accumulated near the margin of East Antarctica. With the breakup of Gondwanaland, the Ellsworth Mountains, and their southern neighbors likely comprised a microplate that translated and rotated to its present position sometime in late Mesozoic or early Cenozoic time. The uplift of the mountains may have accompanied these postulated movements. The geomorphic evolution of the Ellsworth Mountains in Cretaceous and Cenozoic time includes the development of an integrated stream valley pattern and, later, valley and continental glaciation, followed by moderate deglaciation.

Abstract The Taylor Group, the lower division of the Beacon Supergroup, comprises mainly quartzose sandstones of Devonian age deposited after the development of the Kukri Erosion Surface across the Cambrian Ross orogen. Devonian sediments accumulated in a McMurdo Basin that now incorporates most of the Transantarctic Mountains, and a larger Ellsworth Basin that extends from West Antarctica into southern Africa. In southern Victoria Land (McMurdo Basin) the seven formations total around 1200 m in thickness. Sequence stratigraphy suggests five sedimentary cycles, the lower four of which may show shallow marine influence. Provenance studies indicate derivation solely from Ross Orogen sources. The Taylor Group in the central Transantarctic Mountains consists of two thin formations, only one of which is extensive. In the Ellsworth Basin, Taylor Group equivalents rest concordantly on thick piles of post-Ross Palaeozoic sediment. Shallow-water Devonian sediments in the Ohio Range contain a marine fauna linked with those of the Ellsworth Mountains, southern Africa, South America, New Zealand and Australia. A seaway probably existed along the Pacific edge of the East Antarctic craton, allowing these faunal links, and may also have communicated with the McMurdo Basin to drive the five sedimentary sequences.