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II.—Cretaceous Mollusca from New Zealand

Published online by Cambridge University Press:  01 May 2009

C. T. Trechmann
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Extract

Owing to incomplete palæontological knowledge, the true age and correlation of the various divisions of the great Mesozoic series of New Zealand, which, together with the Maitai Series, forms such an important element in the structure of the country, has long remained a matter of uncertainty. In consequence the idea has to some extent taken hold among New Zealand geologists that the Mesozoic faunas, owing to supposed conditions of isolation, show archaic features. It was explained that certain Permian forms occurred in the Trias and that Trias forms may have persisted into Jurassic times, and to a still greater extent that a Cretaceous fauna lived on in this portion of the earth into the Tertiary period.

Type
Original Article
Information
Geological Magazine , Volume 4 , Issue 7 , July 1917 , pp. 294 - 305
Copyright
Copyright © Cambridge University Press 1917

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References

page 294 note 1 Plate XXI will appear with the second part in the August Number.

page 294 note 2 “The Age of the Maitai Series of New Zealand”: Geol. Mag., n.s., Dec. VI, Vol. IV, pp. 53–64, Feb. 1917.Google Scholar.

page 295 note 1 The Geology of New Zealand, 1910, sketch-map.Google Scholar.

page 296 note 1 Nature, 03 22, 1917, p. 79.Google Scholar.

page 296 note 2 Similar concretions occur at Hampden, in North Otago, in beds apparently of the same age that crop out on the seashore. The concretions are surrounded by a casing of stony material in which the finest cone-in-cone structure I have ever seen is developed. The apices of the cones as a rule are directed towards the centre of the nodule, and the bases of the cones on the outside assume forms that suggest floral structures. The outer skin of the septaria is a few inches thick and is generally loose and detached from the concretion and is easily broken off. This together with the presence of yellow calcite veins which pass in all directions through the septaria suggests that the cone-in-cone structure is connected with a contraction of the inner portion of the septarian concretions. These large septarian nodules are rather sparingly distributed in a bed of blackish-grey calcareous shale which shows no trace of cone-in-cone structure. I noticed in some places that where the concretions had been affected by subsequent pressure in the bed the action of the pressure tended to obliterate again the cone-in-cone structure in the outer layer of the nodules.

page 298 note 1 “Relations between Cretaceous and Tertiary Rocks”: Trans. N.Z. Inst., vol. xlviii (new issue), p. 114, 1915.Google Scholar.

page 299 note 1 Berichte der Naturf. Gesell. z. Freiburg, Bd. xv, p. 37, pl. vii, figs. 2, 3, 1907.Google Scholar.

page 300 note 1 Fig. 15 is × 2 nat. size.

page 301 note 1 “Die Anneliden, Bivalven, u. Gasteropoden der antarktischen Kreide, 1910”: Wissensch. Ergebnisse der Schwed. Sudpolar Exped., p. 77, pl. iii, figs. 28a, b.Google Scholar.

page 302 note 1 Trans. N.Z. Inst., vol. xlviii, p. 118, 1915.Google Scholar.

page 303 note 1 Berichte der Naturf. Gesell. z. Freiburg, Bd. xv, p. 18, pl. iv, figs. 2a, b, 1907.Google Scholar.

page 304 note 1 für Min, N.J.., Beil. Bd. xviii, pl. xviii, fig. 1, 1904.Google Scholar.