The Jurassic period witnessed a wider extension of these lacustrine deposits. Walkom (1918) shows them as stretching from the Cape Yorke Peninsula southwards and to the northern parts of South Australia and of New South Wales. He is of the opinion that this basin discharged into the sea by some outlet to the north, and was not connected with a south-eastern sea by a Queensland Gulf such as Neumayr had supposed. A second basin is that comprising the Jurassic coalfields of Victoria and eastern Tasmania, which Walkom thinks may have drained into the Southern Ocean. The intervening region of the present Tasman Sea, hc considers, was probably for the most part a land area, the coast of which lay east of New Caledonia (which was land till near the close of Jurassic times), but west of New Zealand, which formed the littoral zone across which the strand fluctuated (until the early part of Cretaceous time), producing intercalated marine and fresh-water deposits, the latter predominating in the latter part of the period. The comparison of the work of Walkom on the Australian flora, and of Arber on that of New Zealand, briefly summarized by the writer (Benson, 1919), indicates a very general similarity, though with comparatively few forms common to the two regions. In general, also, the Australian Mesozoic flora contains four times as many species as that of New Zealand, perhaps due to the unfavourable littoral habitat of the latter, and the modifications which have ensued during their migration back and forth with the fluctuation of the coast-line. The general conditions indicated continued until the commencement of the Cretaceous period, the highest plant-beds in this series in New Zealand being those of Waikato Heads, which Arber considers of Neocomian age; in these, associated with Cladophlebis and Taeniopteris, appear angiospermous leaves (Artocarpidium), which seem to be more related to the figs than to any other modern plants. Of about the same age as these are the much larger floras described by Walkom (1919) from the Burrum and
Styx River beds in Queensland. The former contains thirty-six species, a typical Wealden association, free from angiosperms; the latter, which probably belongs to a slightly higher horizon, contains three angiosperms out of fourteen forms. Both these Queensland floras contain Microphyllopteris, a genus instituted by Arber (1917) to receive one of the forms present at the Waikato Heads. Walkom (1919), indeed, remarks on the resemblance of the Styx River flora to that of Waikato Heads.
We thus see the grounds for Arber's conclusion that “in Rhaetic and probably also Jurassic times New Zealand and Tasmania were united with Australia as one large connected land area. The flora of these now separated regions are nearly allied but not identical, but the similarity between them is probably sufficient to allow of this hypothesis.” Further,
we must note his remark that “as regards Antarctica, we have no evidence as yet of any Rhaetic land there, but in Jurassic times Graham's Land may have been connected with New Zealand and also with Australia.” Nevertheless, we must recall that the Mesozoic flora was a remarkably cosmopolitan one, and accordingly the provincial affinities must be unusually clear to give much support to palaeogeographic hypothesis. Special interest attaches, therefore, to the form Linguifolium, which was supposed to belong to Glossopteris prior to Arber's investigations.* It occurs in the
[Footnote] *The late Dr. Arber concluded that “there is no evidence that New Zealand formed part of Gondwanaland”; but this, in Seward's opinion, is open to question. “The leaves on which the genus Linguifolium is founded are, I believe, generically identical with, or at least closely related to, Glossopteris. There is, moreover, a close resemblance shown by several New Zealand species of plants with those of the Rhaetic floras of Tonkin, South Africa, and elsewhere, which contain representatives of Glossopteris or other members of the later flora of the Gondwana continent” (Seward, 1914, p. 39). Arber's (1917) reply to this criticism should also be noted.
Rhaetic and Lower Jurassic beds in New Zealand, and Arber believes the genus is represented in the Rhaetic beds of South America and the Jurassic of Australia, though Walkom does not concur in regard to the last. It is perhaps also represented in the Noric beds of New Caledonia by leaves stated by Piroutet (1917) to be “like Glossopteris.”
Leaving the land area, we return to trace the Australasian coast-line north-westwards from New Zealand. The most extensive development of strata of this age is that of marine and fresh-water beds which cover the south-eastern portion of the Dominion, and in their gently undulating character are so different from the adjacent steeply folded strata of the Hokonui Hills and the Alps farther to the north as to suggest that they represent a transgression of the Jurassic sea over a resistant mass—either a promontory of the ancient continental platform or a foreign block in the broad geosynclinal region splitting apart the Takitimu and Hokonui Ranges. The affinities of this fauna have recently been made more clear by Trechmann and Spath (1921), but an abstract only of their work is as yet available.* The series, which is probably about 10,000 ft. in thickness, ranges from Lower Liassic to Upper Jurassic. The affinities exhibited by the fauna are with forms occurring in the Argentine, Andes, Western Australia, Sula Islands, Spiti Shales, and Kutch, while the ammonites which are referable to the Middle Lias have a typically Mediterranean aspect. The highest portion of the series occurs at Kawhia, and fossils from here have been studied also by Boehm (1911), who recognized, besides the circumpacific types of Aucella, Lima, Inoceramus, and Phylloceras, previously noted by Zittel and Hector, additional forms—a Streblites and Perisphinctes—and stated that the well-known Ammonites novozealandicus (Hauer) was a species of Hoplites (Berriasella). Upper Jurassic marine beds underlie the Neocomian plant-beds of the Waikato Heads, and this association, noted by Hochstetter and Cox, has been redescribed by Gilbert (1921)
On the eastern flanks of the main’ ranges of the North Island, however, the upper portion of the older Mesozoic series is a considerable thickness of sparsely fossiliferous greywacke containing Inoceramus. In the Gisborne district these beds have also yielded an obscure species of Turritella which appears to resemble (fide Marwick) some forms recently described by
[Footnote] * Since writing the above the author has been permitted by Dr. Trechmann to see and cite from portion of the manuscript of his unpublished paper, from which the following facts are culled. The oldest of the Jurassic fossils in New Zealand were obtained from beds in the Hokonui Hills, in the South Island, apparently transitional between the Otapiri and Bastion series of Hector (see table, Benson, 1921, p. 59). They contained, with Pecten, Astaite, Tanciedia(?), and Oxytoma, some species of the Hettangian (basal Lias) ammonite Wachneroceras. At a higher horizon in the Bastion beds of the same region, the “Plagiostoma” (Pseudomonotis?) beds contained some rather obscure lammellibranchs and Rhynchonellidae with a “Callovian” (Middle Jurassic) aspect. These are followed by beds with a fauna analogous to that of Kawhia Harbour, in the North Island, where are developed Aucella spitiensis, Arca (Parallelodon) egertonensis. A. blanfordiana, Inoceramus haastii (allied to I. galoi), Tereb [ unclear: ] atula octoplicata, and Rhynchonella pulchi [ unclear: ] ima, a group of Bathonian (Lower-Middle Jurassic) forms, together with forms of Phylloceras like P. passati and P. malayanum, described by Boehm from the Oxfordian (Upper-Middle Jurassic) of the Sula Islands. Trechmann's provisional determination, cited by Gilbert (1921), of the fossils in the beds immediately underlying the “Neocomian” flora of Waikato Heads, a short distance to the north, shows the presence of the lamellibranchs of this group. A higher series of beds in the Kawhia Harbour, of Kimmeridgian-Tithonian (Upper Jurassic) age, is characterized by Streblites cf. motutaranus, Perisphinctes spp., and Belemnites spp, which are also represented in the Sula Islands. The absence of this fauna from beneath the Neocomian beds of Waikato Heads suggests the existence of a hiatus in the Jurassic series there
Etheridge (1920) from the Rolling Downs beds of Queensland. These rocks are termed the Awanui or East Coast series, and with them we may perhaps group the Manaia series of greywackes and conglomerates in the Coromandel Peninsula. The East Coast series are believed by Mr. Morgan to have been formed during late Jurassic and early Cretaceous times, immediately preceding the retreat of the sea prior to the intense orogeny which occurred in Lower Cretaceous times.
In New Caledonia the land exposed by the retreat of the sea in Rhaetic times endured until near the close of the Jurassic period, when a transgression occurred, the strand-line moving from west to east. The incoming marine fauna contained a Berriasella closely allied to B. novozealandicus (Piroutet, 1917). Thus regression in New Zealand, with the formations of the plant-beds of Waikato Heads (the prelude to the early Cretaceous orogeny), followed hard on the transgression of the strand in New Caledonia, but the trangression was of short duration. In eastern New Guinea (Papua) a marine trangression occurred in Middle (?) and later Jurassic times. Etheridge (1889) described some poorly preserved forms from the Fly River which he referred to Stephanoceras cf. calloviensis,* S. aff. lamellosum, S. cf. blagdeni (or S. cf. coronatus), Macrocephalites sp., and Belemnopsis sp. Haug (1911) reports the occurrence of these forms also, but appears here, as in other cases, to have assigned what seemed to be the most probable names to figured and provisionally determined fossils. In northern and south-western New Guinea the same series appears to extend. Boehm (1906) places the formations as ranging from Callovian to Lower Cretaceous, and has determined a number of better-preserved fossils. Of these, Macrocephalites keeuuensis a and M. keeuwensis β-γ are believed to be the equivalents respectively of the first two of the above list of forms determined by Etheridge (Boehm, 1913). Phylloceras, Stephanoceras, Sphaeroceras, Perisphinctes, Hoplites, Oppelia, Hamites (?), Belemnites Posidonomya (?), Inoceramus, and Rhynchonella aff. moluccana are also recognized by him. The same geologist has traced this fauna westwards into the Sula Islands, Buru, Babar, Timor, and Rotti, thus surrounding the Banda Sea. In these there is an indication of a distinctively equatorial sea of about Callovian age, an extension of the Tethyan syncline marginal to the Australasian massif (Boehm, 1907). There is, however, an important southern epicontinental extension of the sea which flooded over the western parts of the Australian continent (which must then have extended farther to the west), producing a thickness of about 2,000 ft. of shallow-water deposits, yellow, brownish, or reddish calcareous sandstone, occasionally plant-bearing (Arber, 1910; Walkom, 1921), passing locally into yellow limestone. Moore (1870) recognized twenty European species with nine new forms, and considered the beds to be of Oolitic age. Crick (1894), as a result of his examination of the cephalopods, considered the beds as belonging to the Lower Oolitic period. He recognized species of Stephanoceras, Dorsetensia, Perisphinctes, and also Belemnites canaliculatus. Chapman (1904) supported this. Boehm (1907) remarked that the fauna was mid-European in its facies, and considered it to have been deposited in the Callovian extension of the equatorial Tethys. Haug (1911, p. 1045) believed the Bajocian and Callovian strata were represented here. Etheridge (1910) added a few more European forms to the list of Western Australian forms, which was completely tabulated by Glauert in the same year. Trechmann and Spath have noted
[Footnote] * Kepplerites calloviensis, according to Haug (1911).
several features of community between the Western Australian fauna and that of New Zealand.
It is interesting to note that Neumayr (1883) was of the opinion that Australasia and China were connected during Jurassic times into a single continental mass; but the discovery of the Malayan developments of the marine fauna has caused certain authors—e.g., Lemoine (1906) and Haug (1911)—to substitute the conception of an Australo-Indo-Madagascan continent, over which there transgressed epicontinental seas into Western Australia and the Runn of Kutch during the Bajocian - Callovian epoch. Uhlig (1911) recognized in this a western development of the Mediterranean-Caucasian faunal province which merged into the Himalayan, of which he regarded as extensions the West African, West Australian, and New Zealand developments. These exhibit marked affinity with the faunas of the Japanese and South Andean provinces, though the contrast they show with the boreal and North Andean province prevents us recognizing a circumpacific geosyncline. The conclusions of Trechmann and Spath (1921) accord with this, and thus are not opposed to the hypothesis of a Jurassic land connection between South America and Australasia suggested by palaeo-botanical evidence, and, according to Hedley (1911), by modern biogeography.
A further conception of Neumayr's must also be considered. Hedley (1909) has restated it from a biogeographic standpoint as follows: “A meridional crease in the earth's crust produced in Jurassic times a gulf, which he called the Gulf of Queensland, whose western shore transgressed the present east Australian coast. Enlarging through geological cycles, this gulf grew into what we know now as the Tasman and Coral Seas…. As the Mesozoic sink enlarged its periphery it became a dominant factor in land-configuration. First it broke through an inner earth-fold of which New Caledonia and the Louisades are relics. Then, continuing its work to the eastwards, it submerged a younger outer continental ridge on which the Solomons stand. Westerly it crumpled up the former coast of north Queensland, and by a further western effort broke open Torres Straits. While the Coral Sea was yet a prolongation of the old gulf, it offered a refuge to old forms of life. The low latitude afforded a warm unchangeable climate, and the surrounding continental extension (New Guinea — New Zealand) secluded its inhabitants from the incursion and competition of other tropical fauna. When, however, continued subsidence to the east at last burst through the Melanesian plateau, a flood of active competitors must have swept in from the open Pacific…. With the opening of Torres Straits, and the consequent outgoing current, the Queensland fauna was spread along north Australia to the Moluccas.”
Walkom (1918), in discussing the above, points out that the late Triassic foraminiferal beds near Sydney form the most important piece of evidence of the existence of this gulf, and “there is no evidence at all to show that this gulf transgressed the present east coast of Australia during Jurassic time…. The gulf was probably more or less coincident with the present position of the Thomson Trough, but whether this trough is as old as Lower Mesozoic is difficult to determine.” His palaeogeographic map (1918, fig. 5) illustrated his conclusion that during Jurassic times the eastern coast of Australasia remained in much the same position as it was in during the Triassic period,* and to the south the Gulf of Queensland disappeared, or was very much reduced.
[Footnote] * Piroutet's conclusion concerning the Jurassic emergence of New Caledonia was not available at the time Dr. Walkom wrote.
Lyman Clarke's (1921) study of the modern echinoderms of Torres Straits has led to the following conclusions: * “Hedley's hypothesis of a Queensland Gulf in Mesozoic time receives no support from the echinoderms. What may be called the original echinoderm fauna was on the north-west side of the present continent, and was of East Indian origin and Indo-Pacific composition. On the other hand, confirmation is afforded for Hedley's view that, as land areas east of New Guinea subsided, the Coral Sea became connected with the Pacific; its western shores also receded until the Great Barrier Reef was formed. This sea was invaded by echinoderms from the Pacific…. Continued subsidence on both sides led at last to the formation of Torres Strait, and the East Indian echinoderms then migrated eastward and southward to the Queensland coast, where they mingled with Pacific immigrants. The latter, however, had not passed westward through the straits.” (Parenthetically, we may here recall the strong physiographic evidence of the westward retreat of the Queensland coast to its present position in comparatively recent times: cf. David, 1911.)
[Footnote] * Review by F. A. B. in Nature, 4th August, 1921.