1919.] Morgan.—Permo-Carboniferous (Maitai) Rocks. 
33 
PERMO-CARBONIFEROUS (MAITAI) ROCKS OF THE 
EASTERN PART OF THE SOUTH ISLAND OF 
NEW ZEALAND. 
By P. G. Morgan, M.A., F.G.S. 
Hector and McKay referred a large portion of the older rocks on the 
eastern side of the main watershed of the South Island to the Maitai 
Series, which they considered to be of Carboniferous age, but which, as 
shown by Trechmann and others, may be correlated with the Permo- 
Carboniferous rocks of New South Wales.* This was done partly on 
account of the sporadic occurrence of a supposed species of Inoceramus 
identical with a similar organism in the Wairoa and Dun Mountain 
limestones and argillites, partly on account of the widespread occurrence 
of one or more species of annelid in rocks lithologically similar to 
some of the Maitai rocks, and partly because there was no special 
reason for giving the rocks in question any other classification. Thus 
McKay in discussing the geology of the Kaikoura and Looker-on 
Mountains says that he has included in the Maitai Series some of the 
Kaikoura rocks which he suspects do not belong to the series, for 
the reason that his predecessors had done so, and that he was not 
warranted in changing their classification until fully satisfied that the 
rocks were younger. 
Park and Marshall, however, starting with the fact that large areas 
of rock with undoubted Trias-Jura fossils occur, whereas the supposed 
Maitai rocks were known to contain only an Inoceramus-like shell and 
some annelids, have placed all the so-called Maitai rocks on the eastern 
side of the main divide of the South Island in the Mesozoic For some 
time an undefined area in north-east Otago near Mount St. Mary formed an 
exception to this statement so far as Park was concerned, and was classed 
by him as Permo-Carboniferous. As regards the Maitai rocks, however, 
both in Nelson and elsewhere, he wrote, “ It seems impossible for any 
student of geology to seriously maintain a Carboniferous age for a formation 
characterized by such a truly Mesozoic genus as Inoceramus A few 
years later the authors of the Dun Mountain bulletin argued similarly, but 
threw a shadow of doubt on the identification of Inoceramus in the 
Dun Mountain rocks. They say, “ The occurrence of Inoceramus fragments 
in such numbers, if correctly identified, goes far to justify the correlation 
of these strata with the Middle Mesozoic era.”J 
* According to A. B. Walkom (in “ The Geology of the Lower Mesozoic Rocks of 
Queensland,” Proc . Linn. Soc. N.S.W., vol. 43, pt. 1, p. 96, 1918), T. W. David and 
W. S. Dun suggest that perhaps the term “ Permo-Carboniferous ” in Australia should 
be replaced by the term “ Permian.” 
t James Park, On the Jurassic Age of the Maitai Series, Trans. N.Z. Inst., vol. 36, 
p. 443, 1904. 
t J. M. Bell, E. de C. Clarke, and P. Marshall, The Geology of the Dun Moun¬ 
tain Subdivision, Nelson, N.Z. Geol. Surv. Bull. No. 12, p. 18, 191 i. 
3—Science. 
