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Chapter IV. 
THE GNEISSIC ROCKS AND CRYSTALLINE LIMESTONE. 
As the gneissie rocks occur at sea-level at the foot of the highest part of the 
Royal Society Range, and as they are found in the Range below a sequence of 
rocks which is 12,000 feet thick, they may be safely regarded as forming the 
ancient platform on which the central part of South Victoria Land is built. 
Above the gneisses, come successively, over a very large area, granites, sandstones 
and clolerites. Little is known of the field-relations of these except the order in 
which the rocks occur. The important deposit of sandstone provides a convenient 
stratigraphical datum-line, with reference to which the positions of the other rocks 
will be considered. The above order seems, however, to be chronological, for, 
where the junctions between any two rocks were examined, the lower rock usually 
appeared to be the older. With regard to the gneissie series, the localities at which 
they have been examined may be considered in three groups : — 
(1) The Foothills of the Royal Society Range. 
(2) The Kukri Hills. 
(3) The Cathedral Rocks. 
The Southern Foothills (Fig. 11). 
South Side of the Blue Glacier. 
On the hill J 1; * 5400 feet high and 15 miles from the sea, occur masses of crystalline 
limestone which rise at least 1000 feet above the snow. The limestone is almost pure 
white, and the constituent crystals are often an eighth of an inch across. It becomes 
so crumbly, on weathering, that it is difficult to get a hand-specimen from the 
rounded surfaces that are exposed. 
The rock (568) has important structural planes which dip at 70° to the east, 
while the strike is north-and-south. The hill appears to be wholly composed of 
limestone ; its western slope is very straight and steep, and is suggestive of a 
fault. Parallel to the bedding-planes or, more probably, joint-planes are bands of a 
dark fine-grained hornblende-biotite-granite (569) from 4 inches to 2 feet in thickness 
and about 50 yards apart. At this spot there were no obvious metam orphic features 
near the junction of the two rocks. 
* For localities indicated by letters, see tlie map of the district near the 1 Discovery ’ Winter Quarters, and the 
sections in Plate VII. 
VOL. i. 
E 
