54 SEASONAL DEPOSITION IN AQUEO-GLACIAL SEDIMENTS. 
‘banding mentioned with other tillites, this specimen is especially important. 
It may be well to quote Hatch and Corstorphine on this formation: 
“The Griqua Town series is divided by Mr. Rogers into an upper group, consisting 
largely of slaty rocks, together with some brown and red jasperoid rocks and thin beds of 
chert and limestone; a middle group, consisting for the main part of the Ongeluk volcanic 
beds, together with some banded jasper beds; and a lower group, comprising banded jaspers, 
quartzites, and mudstones. The conglomeratic rocks that occur at or near the top of the 
lower group in the Hay district contain ‘striated and flattened pebbles and boulders,’ which, 
according to Rogers, ‘ certainly owe their characteristic shape and scratches to glacial action.” 
Hatcu & CorstorPHInE, 1909, p. 148. 
Concerning the sediments which lie just above the tillite, Rogers (1906) 
notes: 
“At Monjam, Mabedi, there are some twelve feet of thin-bedded dark quartzitic rock 
lying between the highest outcrops of the glacial beds and the lowest Ongeluk lavas.” 
Rogers, 1906, p. 43. 
The age of this glacial series is still in question, but Rogers proves that it is 
older than the Dwyka and it is possible that it may be as old as pre-Cambrian. 
It looks very much as if these banded metamorphosed sediments might have 
the same origin as the Squantum banded glacial clays. 
The ancient tillite discovered by Reusch in Varanger Fiord, Norway, rests 
on a sandstone which was already consolidated at the time of the deposition 
of the tillite as shown by well-marked glacial grooves on its upper surface 
(Strahan, 1897, p. 1387-146). This tillite is overlain by a sandstone of a ‘‘regu- 
larly bedded” nature. Although there is no description of alternating coarse 
and thin beds, they may be present. This tillite is of unknown age but prob- 
ably pre-Cambrian. 
Lying on’the Cambrian or pre-Cambrian tillite which Willis and Black- 
welder discovered at Nan-t’ou on the Yangtse River in China is a thin sheet 
of conglomerate (Willis, 1907). Above this conglomerate comes about 250 
feet of rather thin-bedded argillaceous limestones. Whether there is good 
banding similar to that I have described it is not possible to say. It is very 
evident, however, that this tillite reached sea-level as determined by marine 
fossils, and it is more than likely that wave action or tidal scour destroyed most 
of the lamination, for Blackwelder mentions only a few feet of lamination above 
the conglomerate. 
In South Australia near Adelaide, Howchin describes the tillite of lower 
Cambrian age as follows: 
