FROM THE MAINLAND OF SOUTH VICTORIA LAND 205 



sandstone to a highly felspathic arkose. The former is the typical Beacon Sandstone 

 described in Dr. Prior's reports.* In point of general description nothing remains to 

 be recorded more than is therein detailed. Exceptional features are, however, abundant 

 and worth notice. 



The usual characters are a medium-grained sandstone composed of angular or 

 somewhat rounded grains of quartz usually but loosely cemented together ; accessory 

 ingredients such as felspar, garnet, and rutile are quite common. The cementing 

 materia], usually siliceous, is frequently calcareous. The typical sandstone passes over 

 on the one side to conglomerate or arkose and on the other to much fine grained 

 saccharoidal varieties (Fig. 1, Plate I). 



A sample of this latter variety, from Dry Valley, grades from a very white sac- 

 charoidal sandstone above into a band below, studded with partially abraded quartz 

 pebbles as much as 18 mm. long. The sand grains are sub-angular, frequently exhibiting 

 shining crystal faces, and are but loosely adhering. Quite fresh felspar grains are not 

 uncommon. The grain size averages 0-75 mm. A crystal of gypsum was noted 

 adhering to the wall of a cavity in this specimen. 



In a specimen from the Lower Medial Moraine, Ferrar Glacier, fragments of grey- 

 blue shale appear. These exactly resemble similar inclusions in the psammites of the 

 older glacial horizons of Australia. Some specimens collected opposite the Cathedral 

 Rocks, Ferrar Glacier, are highly felspathic ; some are strongly and others loosely 

 cemented. 



In some specimens the grains are much more rounded, as in the case of a very white 

 rock from Knob Head Mountain Scree, Ferrar Glacier, in which the quartz grains are 

 embedded in a kaolin base. 



This latter type is usually closely associated with carbonaceous varieties. A 

 specimen of such a rock from the moraine below Cathedral Rocks contains quartz, 

 some felspar, and occasional faintly pink garnet in fairly well rounded grains. The 

 carbonaceous matter follows along certain planes of deposition associated with 

 accumulations of silt. Muscovite plates are conspicuous along these planes. 



An exceptional tinted variety is one from the Medial Moraine, Ferrar Glacier, 

 where the interstices are filled with a chloritic substance contributing a greenish 

 colour. 



Quartzites of essentially the same characters but almost flinty in fracture, met with 

 amongst the moraines of the Ferrar Glacier, are regarded as Beacon Sandstone meta- 

 morphosed, probably by local igneous action. 



Ferrar and Prior f have referred to stalagmitic and marbled forms of the Beacon 

 Sandstone. This is due to unequal cementation in the sandy beds, perhaps resulting 

 from local infiltration of alkaline solutions. Weathering processes often result in 

 stalagmitic relief ; at other times concretionary forms are developed. Numerous 

 examples of the latter occur in Priestley's collections from the Knob Head Mountain 

 Scree, and from the Medial Moraine opposite Cathedral Rocks, Ferrar Glacier. These 

 concretionary nodules are spherical (Fig. 2, Plate I) and saucer -shaped (Fig. 3, Plate I). 

 The former, though cemented firmly in the peripheral zone, often contain within much 

 calcareous and clayey matter. The central portions are thus but loosely cemented. When, 

 in nature, fracture of the hard shell takes place, due to accidental circumstances, the 

 softer central portions are quickly removed by wind erosion and the concretions are 

 hollowed out (Fig. 2, Plate I). In situ, these concretions appear either as spherical 

 balls in relief or, where hollowed out, as wells sunk in the weathered surface. On 

 slicing a completely spherical specimen 7 cm. diameter it was found to consist of an 



* British Museum Reports on National Antarctic Expedition, 1901-4, vol. i. Geology. 

 | Ibid., p. 139. 



