The Jurassic Rocks of New Zealand

The Jurassic in New Zealand comprises a thick series of deposits, important both stratigraphically and structurally. In every locality where the sequence is well seen they follow closely the Triassic rocks with apparent perfect conformity. Compared with the underlying Trias, however, they exhibit contrast in a number of characters, among which are the following:— ( a ) They are, generally speaking, less steeply inclined and enter less, so far as is at present known, into the structure of the Alpine mountain-ranges. No instance is known to me where rocks with recognizable Jurassic fossils occur in a slaty or semi-metamorphic condition as do the Triassic rocks in some places on the eastern fringes of the Southern Alps: for example, at Mount Potts and Mount St. Mary. ( b ) The Jurassic, in contrast with the Trias, exhibits a much greater vertical range of marine fossiliferous deposits throughout its thickness, including horizons ranging from the lowest Lias to the Kimmeridgian and Tithonian. The Trias, on the contrary, is fossiliferous only in the higher beds, ranging from the Ladino-Carnic to the Rhaetic. ( c ) Jurassic rocks apparently occur over a rather greater length of the two islands than the Trias, although this is probably due merely to accidents of outcrop and exposure, since Trias much resembling that in New Zealand recurs in New Caledonia. The Jurassic rocks at Waikawa occur at the extreme south-eastern corner of the Soufch Island, and near the northern extremity of the North Island at Cape Maria van Diemen and Spirits Bay Mr. A.