Walcott Formation

Schmidt and Ford (1969) mentioned that a thin layer of marble in the Mt. Walcott Formation contains stromatolites. However, Storey and Macdonald (1987) and Pankhurst et al. (1988) later stated that these stro-matohtes are actually composed of interlaminated calcareous siltstone and limestone that underwent soft-sediment deformation. The same authors did find abundant echinoderm plates and sponge spicules similar to Protospongia fenestrata which occurs in the Middle Cambrian Nelson Limestone of the Pensacola Mountains (Weber and Fedorov 1980, 1981). The Mt. Walcott Formation also contains trace fossils (Planolites and Chondrites). Although Planolites has been found in rocks that are 1,000 milhon years old, the earhest appearance of Chondrites is in rocks of Cambrian age. Therefore, Pankhurst et al. (1988) concluded that the paleontological evidence supports a Phanerozoic age for the Mt. Walcott Formation, whereas Schmidt and Ford (1969) had previonsly assigned it a probable Neoproterozoic age. 

Mt. Walcott Formation Flat-lying, thin-bedded clastic sedimentary rocks of low metamorphic grade interbedded with thin dacite flows or siUs. Total thickness about 1(X) m... 

The Thiel Mountains are part of the far-eastern mountains that extend from the Ohio Range of the HorUck Mountains to the east coast of the WeddeU Sea. The rocks exposed along the north-facing escarpment of the Thiel Mountains consist of undeformed sedimentary rocks of low metamorphic grade (Mt. Walcott Formation) that are overlain by the cordierite-bearing hypersthene-quartz-monzonite porphyry of the Thiel Mountains Porphyry. This unit is a massive deposit of crystal-rich silicic tuff that contains cordierite and hypersthene as xenocrysts and in small granuhte xenoliths. The presence of cordierite in this volcanic or shallow intrusive... 

Fig. 10.14 The southern part of the Queen Alexandra Range in Fig. 10.13 exposes the Fremouw and Falla formations of the Beacon Supergroup as well as the overlying Prebble Formation and Kirkpatrick Basalt of the Ferrar Group. This part of the Queen Alexandra Range is located west of the Beardmore Glacier and east of the Walcott Nive. Excerpt of the Buckley Island (S V 61-60/3) and Cloudmaker (SV 51-60/4) topographic maps of Antarctica. US Geological Survey, 1967, Washington, DC...

Fig. 19.5 (a) Mount Sirius in the Beardmore Glacier area (Figs. 11.8 and 11.9) is a mesa composed of sandstones of the Beacon Supergroup overlain by an intrusive sill of the Ferrar Dolerite. The summit consists of a massive deposit of Neogene till which is the type example of the Sirius Formation as originally defined by Mercer (1972). The elevation of Mt. Sirius is 2,300 m above sea level compared to 2,000 m on the Walcott Ndvd (Photo by G. Faure). (b) The Neogene lodgement till on the summit of Mt. Sirius was... 

Formation, Bighorn Mountains, Wyoming (b) Reconstruction of Astraspis desiderata Walcott, based upon data provided in Sansom et al. (1997). 

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