Maitai Series of New Zealand. 55 



which, might decide the question whether the shell is really 

 Inoceramus or not. 



Structure and Tectonics. 



The Maitai Beds are a series of great structural importance since 

 they, or at any rate rocks referi'ed to this series on lithological and 

 stratigraphical grounds, enter largely into the composition of the 

 Alpine ranges of the South Island. It is only, however, in the 

 Nelson district where fossiliferous limestones occur in the Maitai 

 that any fossils other than the prismatic shell fragments and possibly 

 some annelid tubes have been found in these beds. 



McKay records nine localities where fragments of this prismatic 

 shell have been found. Similar fragments occur in limestone on the 

 Cass River and the Upper Waimakariri in the Canterbury Alps. 1 



The relation of the Mt. Torlesse annelid beds, which by the way 

 are said not to occur actually at Mt. Torlesse, to the Maitai Series is 

 one of the most difficult problems of New Zealand geology. McKay 

 discusses this question, 2 and the general opinion seems to be that the 

 annelid-bearing rocks belong to the upper part of the Maitai Series. 



A great series of greywackes and other beds forms the ranges of 

 the Rimutaka, Ruahine, and Tararua Mountains on the eastern side 

 of the North Island. Dr. Thomson has recently found annelid 

 remains in these beds near Wellington. 



In other places the Maitai Beds become partly or completely 

 metamorphosed. McKay 3 reports their occurrence in a semi- 

 metamorphic condition in the heart of the Southern Alps west of 

 Lake Whakatipu. When in this condition they are not easily 

 distinguished from the underlying or partly equivalent Te Anau 

 Series. However, both the Te Anau and the Maitai Series are newer 

 than the rocks which at Mt. Arthur and Reefton contain a Silurian or 

 possibly Devonian fauna. 



McKay, after a detailed study of the Nelson area concludes, though 

 with considerable reserve, that the Maitai Beds are arranged in 

 a syncline with the main axis N.N.E. and S.S.W., in which case the 

 limestone must underlie the slates and argillites of Wooded Peak. 

 This limestone crops out near the top of the lower part of the Wairoa 

 Gorge, where it forms the eastern boundary of the fossiliferous Trias 

 beds. A limestone again appears on the eastern side of the slates and 

 argillites on Wooded Peak, five miles east of Nelson, where, though 

 unfossiliferous, it strongly resembles that of the Wairoa Gorge, and 

 1 have little doubt is the same bed. 



No locality is known in New Zealand which reveals clearly the 

 relation of the Trias to the beds underlying it. The Nelson area, the 

 critical one for the study of the Maitai Beds, is very complicated. 

 The Trias beds which form the foot-hills seem to consist of a long 

 faulted synclinal strip, to the east of which, between them and the 

 serpentine and dunite intrusion of the so-called Mineral Belt, the 



1 McKay, "Ashley and Amuri Counties" : Rep. Geol. Expl. for 1879-80, 

 issued 1881, p. 88. 

 3 Ibid., pp. 89-90. 

 1 Ibid., " Lake County," p. 142. 



