338 THE VOYAGE OF THE 'DISCOVERY 5 [Appx. 



The Beacon Sandstone was also examined at the foot of Finger 

 Mountain, in the Dry Valleys at the foot of Beacon Height West, 

 and at the foot of Knob Head Mountain. In character it is mar- 

 vellously uniform, and the horizontal bedding planes have seldom 

 been tilted by the intrusive sheets of dolerite. Locally the beds 

 have been disrupted, but, as masses have been lifted bodily, no 

 great changes in the character of the rock have been produced. 



The relation of the dolerite to the sandstone can perhaps be 

 best studied at Finger Mountain. Here dykes are displayed cut- 

 ting upwards across the bedding planes of the sandstone, sills 

 forcing their way between the strata, or even pipes which appear ■ 

 to feed the superincumbent sheets. 



The Beacon Sandstone as a whole is very uniform in texture, 

 but the grains of quartz are not very firmly packed together. 

 Locally it becomes almost a quartz grit, or again, arkose 

 characters are developed. Current bedding and collections of 

 quartz pebbles appear and disappear quite suddenly in the 

 mass, and these may even form part of the carbonaceous seams. 

 Only at one spot did the rock become calcareous, and the 

 calcite, by cementing the quartz grains together, produced a 

 more durable rock, which therefore projected as a shelf beyond 

 the remainder. 



This calcareous band is only about four inches thick, and as it 

 occurs near the top of the sandstone, and as such abundant traces 

 of organic matter occur in the sandstone blocks at the foot of 

 Depot Nunatak, it is highly probable that this vicinity will yield 

 more abundant organic matter than any other. A nunatak higher 

 than Depot Nunatak, and about six miles from the south of it, 

 displays dark bands in what is possibly the Beacon Sandstone, 

 and this spot therefore may be worthy of closer examination in 

 future. 



The two following sections will give a general idea of the nature 

 of the great Beacon Sandstone formation : 



a. At a spot ten miles south-west of Finger Mountain — 

 (8) 700 feet columnar dolerite. 

 (7) 200 „ almost pure sandstone with occasional 



pebbles. 

 (6) 2 „ carbonaceous band with fossils. 

 (5) 12 „ sandstone with brown bands. 

 (4) 12 „ hard white sandstone, with a three-inch 

 fibrous strip. 



