Speight. — The Intermontane Basins of Canterbury. 349 



movements have taken place in its vicinity is evidenced by the fault fissures 

 of recent earthquakes, and by the peculiar strip of folded-in limestone which 

 crosses the Waiau River at Marble Point, just below where the river issues 

 from the basin. 



Canterbury Plains. 



There is a marked resemblance in general features between the aggraded 

 flood-plain of the Hurunui basin and the Canterbury Plains, which perhaps 

 may be regarded as a large intermontane basin, with the mountain barrier 

 absent on the eastern side. There is some evidence that the plains have 

 been formed by the deposit of gravel on a syncline of Tertiary rocks. 



I have noted in the appendix to my paper, " Some Aspects of the Terrace- 

 development in the Valleys of the Canterbury Rivers " (Trans. N.Z. Inst., 

 vol. 40, 1908, p. 40), that there is a probable outcrop of coal-measures beneath 

 the sea of the Canterbury coast, indicated by the frequent appearance in the 

 trawl of the steam-trawler " Nora Niven " of large pieces of lignite or brown 

 coal. These were obtained in depths of between 21 and 43 fathoms on a 

 line following the coast-line and about twenty-five miles distant from it. 

 Beyond the line where these were picked up the sea-bottom rapidly deepens, 

 and it is probable that they have been torn from the edge of a submerged 

 escarpment of Tertiary rocks where the coal will be in position. There is 

 also on Banks Peninsula an outcrop of Trias-Jura rock, similar' to that of 

 the Malvern Hills, with overlying rhyolites of identical lithological composi- 

 tion. This, too, is overlaid, at the head of Lyttelton Harbour, at Quail 

 Island, and at Governor's Bay by quartzose sands, whose age cannot be 

 exactly determined owing to the absence of fossils, but it is perfectly possible 

 that they represent similar sands associated with coal-measures on the 

 western side of the plains. The shales with plant-remains occurring near 

 Gebbie's Pass probably date from the same period. 



A most persistent feature of the Tertiary deposits referred to above is 

 the occurence at their base of a fairly fine conglomerate composed usually 

 of pebbles of the underlying Trias-Jura greywackes. At Mount Somers, 

 Rakaia Gorge, Malvern Hills, and in the Trelissick area rolled fragments 

 of rhyolite of a kind which now forms mountains on the eastern front of 

 the Alps from the Selwyn to the Ashburton River is a notable constituent 

 of this conglomerate. The presence of these rolled fragments shows clearly 

 that the existent masses of rhyolite in close proximity to these sedimentaries 

 were a land-surface of considerable extent at the time when the coal-measures 

 of Canterbury were laid down. 



On the western slopes of the Alps the basal beds of the coal-measures 

 contain an enormous thickness of coarse conglomerates, approximately 

 2,000 ft. {vide Bulletin No. 13, N.Z. Geol. Survey, p. 51). In this publication 

 Morgan says, " Apparently the highlands supported glaciers, for somewhat 

 outside the subdivision rocks corresponding to the basal conglomerates 

 show glacial characters." He also points out that the land which furnished 

 these boulders lay probably to the north or north-west ; that there was then 

 no Grey Valley, no Paparoa Range, and possibly no Southern Alps. As 

 mentioned later, such a land may have formed the sanctuary where the 

 Antarctic and Subantarctic elements in our flora found a refuge, at a time 

 when the site of the present Alps was occupied by land of relatively low 

 elevation. 



It is to be noted besides, in places where the conglomerates do not occur, 

 that sandstone beds at the base of the series are coarse in texture, and are 



