Plates XII., XIII.
Dr. von Hochstetter, in 1864, placed the Wanganui River beds with his Hawke's Bay series, in the younger of the two groups into which he divided our tertiary rocks;1 and he considered them to be of pliocene age. He did not, however, visit the district, and gave no list of fossils obtained from there.
In 1867, Mr. J. Buchanan, of the Geological Survey, made a large collection of fossils from between Wanganui and the Patea, and he divided the rocks into a lower blue clay and upper sandy beds.2 These fossils were examined by Dr. Hector, who placed the upper sandy beds in the post-tertiary, and the lower blue clay in his upper tertiary or Struthiolaria beds, together with the blue clays of Awatere, Motunau, Awamoa, and other places.3
On a re-examination of these fossils, in 1872, I followed Dr. Hector in keeping the upper beds in the pleistocene, but separated the blue clay of Shakespeare Cliff from the other beds associated with it as a separate and younger formation, under the name of the Wanganui Formation.4 This I considered to be pliocene, and the Awatere series to be upper miocene.
In 1875, Mr. A. McKay referred to the Wanganui Formation some conglomerates and highly fossiliferous sands with pumice overlying the Napier limestone, between Cape Kidnappers and the Mariatotara River.5
In 1876, Mr. S. H. Cox ascertained that a considerable thickness of marine strata, with abundance of fossils, mostly recent, were superimposed upon the Napier or Scinde Island limestone, in Hawke's Bay.6 He gave a list of these fossils, which Dr. Hector pronounced to be the same as those from the upper beds at Wanganui, and he placed the rocks in the Wanganui Formation.7
In 1877, Mr. A. McKay traced these beds from the Manawatu Gorge to Napier,8 giving them the name of Rotella beds. In
[Footnote] 1 “Reise der Novara,” Geologischer, Theil I., p. xl.
[Footnote] 2 “Trans. N.Z. Inst.,” vol. ii., p. 163.
[Footnote] 3 “Catalogue of the Colonial Museum,” Wellington, 1870, p. 172.
[Footnote] 4 “Cat. Tert. Moll. and Echin. New Zealand,” Wellington, 1873; and “Quart. Jour. of the Geol. Soc. of London,” vol. xxix., p. 373.
[Footnote] 5 “Rep. Geol. Expl.,” 1874–76, pp. 44 and 49.
[Footnote] 6 “Rep. Geol. Expl.,” 1874–76, p. 96.
[Footnote] 7 “Rep. Geol. Expl.,” 1874–76, pp. viii. and x.
[Footnote] 8 “Rep. Geol. Exp.,” 1876–77, p. 79.
the same year, Dr. Hector, in his new classification of formations, considered the upper beds at Wanganui to be pliocene; and he grouped them with the Hawke's Bay beds as the Kereru Rotella beds, subsequently called the Kereru series.11 The blue clay of Shakespeare Cliff was now called the Wanganui series, and put into the upper miocene. Indeed, the Director of the Geological Survey has never acquiesced in my view that the Shakespeare Cliff clay is younger than the miocene. He has always considered it as upper miocene, placing it formerly with the Awatere series, but last year with the Te Aute limestone; the Awatere series being now made lower miocene.22 It will thus be seen that the terms “Wanganui formation” or “Wanganui series” have been used sometimes for the upper sandy beds, sometimes for the underlying blue clay.
In January, 1884, I examined the Wanganui District, and came to the conclusion that the upper sandy beds cannot be separated from the blue clay; that all are of pliocene age, and very different, palæontologically, from the Awatere series or the Te Aute limestone. Accordingly, in a paper read to the Geological Society of London, in January, 1885, I proposed a Wanganui system to include both; distinguishing the beds at Wanganui as the Putiki series, those at Hawke's Bay as the Petane series, and those on the west side of the Ruataniwha Plains, in Waipawa County, as the Kereru series;33 at the same time saying that these series were geographical only, and did not represent different epochs of time. I had not room in that paper to give all the evidence on which I relied for proving that these series formed a distinct system well marked off, both palæontologically and stratigraphically, from the older Pareora system; and the object of the present communication is to furnish this, together with other evidence, which I obtained during a visit to Hawke's Bay last January. However, in order to save space, I have not thought it necessary to give separate lists of the fossils from each locality, but have contented myself with one list of all the species known from the Wanganui system, with the localities in which each has been found. Kereru I have not visited, and have no list of fossils from there; but, according to Mr. McKay, they are the same as those found at Matapiro Station, on the Ngaruroro River. Of course my visits, both to Wanganui and to Hawke's Bay, were far too short to allow me to work out the stratigraphical relations of all the different beds; but I think that what I have seen, together with the large collections of fossils that I have examined, will be sufficient to lay the foundation for a correct classification of the beds, and will enable local geologists to work out the details.
[Footnote] 1 “Rep. Geol. Exp.,” 1876–77, p. 4.
[Footnote] 2 “Rep. Geol. Expl.,” 1883, p. 13.
[Footnote] 3 “Quart. Jour. Geol. Soc.,” vol. xli., p. 211.