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Making New Zealand vol 01 no 01: The Beginning

A Great southern continent

page 8

A Great southern continent

Terraces cut by glaciers in the Rangitata Valley, Canterbury. V. C. Browne

Terraces cut by glaciers in the Rangitata Valley, Canterbury. V. C. Browne

The earliest European navigators who visited New Zealand came here in search of a Great Southern Continent. Tasman thought he had discovered it; Cook disproved its existence. But millions of years earlier, during a great part of the Mesozoic Era, New Zealand did actually form the shore-line of a great continent, named Gondwana-land, which extended far to the west. The Tasman Sea did not then exist, and New Zealand was joined to Tasmania and Australia.

During this time spoil from the eastern part of Gondwanaland was washed down and deposited on the present site of New Zealand. But, owing to the fluctuations of the continental margin, sometimes it lay beneath the sea, sometimes it formed a low-lying coastal-land with widespread lakes or lagoons. As a result, there were built up coarse
A fossil plant of the Mesozoic Era—a fern-like form abundant enough to be called a Mesozoic weed. A. E. Newell Arber

A fossil plant of the Mesozoic Era—a fern-like form abundant enough to be called a Mesozoic weed. A. E. Newell Arber

marine sandstones and pebble-beds of great thickness which alternated with fresh-water plant-bearing strata.

The marine fossils of the Mesozoic Era reached New Zealand by the ancient sea-way which stretched northwards to New Caledonia, thence page 9 via the Malay Archipelago to the Himalayas (still unborn) and so to the Mediterranean. The characteristic fossils of this era are the spirally coiled ammonites, relatives of the octopus. With them are found extensive banks of mussel-like shells and the last representatives of some Palaeozoic types. Marine Mesozoic rocks are best developed in the Hokonui Ranges of Southland, but they are also found, often without fossils, in other mountainous parts of both islands.

The Mesozoic Era is known not only by fossil animals, but by fossil plants. At intervals during the Upper Triassic and Jurassic Periods the New Zealand area was above sea-level long enough for forests to flourish. The oldest are found in Canterbury—at Mount Potts in the Rangitata Valley and in the Clent Hills. Slightly younger are those in the Malvern Hills, at Mokoia, near Gore, and, most famous of all, at Curio Bay, near Waikawa, Southland. The Curio Bay beds, indeed, are a remarkable example of a petrified forest dating back to Jurassic times. Here the plant-beds are exposed by sea erosion, and the shore-line is thickly strewn with fallen trunks and limbs of petrified trees, many of them over fifty feet in length and two feet across. Even well-preserved impressions of leaves may be found in abundance. Flowering plants had not yet made their appearance and most of these fossils are remains of fern-like plants, cycads (a kind of palm), and conifers.

Mesozoic Era Upper Triassic and Jurassic Periods
The floor of the South-west Pacific, showing that New Zealand still retains submarine connections with northern lands. The sketch shows the depths in fathoms. T. G. Taylor

The floor of the South-west Pacific, showing that New Zealand still retains submarine connections with northern lands. The sketch shows the depths in fathoms. T. G. Taylor

Cycads and fern-like plants, typical of the Jurassic Period. An artist's reconstruction of plant life on land.

Cycads and fern-like plants, typical of the Jurassic Period. An artist's reconstruction of plant life on land.

During his first voyage Captain Cook proved that New Zealand was not part of a Great Southern Continent. This 'Dauphin' map of the world, made by Pierre Desceliers in 1546 to the order of Francis I. of France, for the education of his son, the Dauphin, shows the mythical 'Terra Australis' or Great Southern Continent. Note that the geographers of the period reversed all objects on one side of the Equator.

During his first voyage Captain Cook proved that New Zealand was not part of a Great Southern Continent. This 'Dauphin' map of the world, made by Pierre Desceliers in 1546 to the order of Francis I. of France, for the education of his son, the Dauphin, shows the mythical 'Terra Australis' or Great Southern Continent. Note that the geographers of the period reversed all objects on one side of the Equator.