REPORTS OF RESEARCH COMMITTEES. 341 



Speight has recognised the part played by differential move- 

 ment of faulted blocks in forming large interniontan© basins such 

 as the Waiau-Hiirunui Plain and the Trelissick Basin, and has 

 pointed out confirmatory evidence in thei presence of downthrown 

 outliers of a formerly widespread sheet of young rocks.* In dis- 

 cussing the crientatioii of the river-valleys of Canterbury he has 

 not come to a definite conclusion. f 



Speight has also added considerably to the stock of informa- 

 tion concerning Banks Peninsula, a large double volcano, maturely 

 disisected and partly drowned. The harboursi of Lyttelton and 

 Akaroa he finds are not simply explosion craters, but are large 

 valleys developed by subaerial erosion (prior to drowning) in the 

 hearts of the ancient volcanoes. ;]: He has found additional evi- 

 dence of recent submergence' in the presencei of a buried forest near 



Speight has described coastal features resulting from both 

 retrogradation and progradation along the mai'gin of the Canter- 

 bury Plainll and in North Canterbury has found evidence of uplift 

 (totalling 600 feet) in the presence of both marine shelves and 

 river terraceis.^ 



J. A. Thomson** has ascribed to the larger topographic features 

 in the Waimate (South Canterbury), Maharahara (Hawke's Bay), 

 Clarence Valley (Marlborough), and Waipara (North Canterbury) 

 districts an origin as tectonic blocks during the period of movement 

 termed Kaikoura by Cotton. In the Waihao district he was one 

 of the first in New Zealand to recognise in the smooth back slope 

 of a tilted block a fossil plain of erosion newly stripped of its 

 cover. He has adopted the " antecedent " explanatioai for the 

 gorge by way of which the Manawatu River cresses the back-bone 

 range of the North Island from east to west. In common with 

 other writers, he assigns to some of the rivers of Marlborough and 

 North Canterbury a consequent origin and to others an antecedent 

 or perhaps anteconsequent origin, and finds in the rejuvenation of 

 the valleys evidence of recent uplift. 



* R. Speight, The Intermontane Basins of Canterbury, Trans. N.Z. Inst., vol. 47, pp. 



336-53, 1915 An unrecorded Tertiarv Outlier in the Basin of the Rakaia, 



Trans. N.Z. Inst., vol. 49, pp. 356-60, 1917 Structural and Glacial Features of 



the Hurunui Vallev, loc. cAt. snpra. 



t R. Speiaht, The Orientation of the River-vallevs of Canterbury, Trans. N.Z. Inst., vol 

 48, pp. 137-44, 1916. 



J R. Speight, The Geology of Banks Peninsula Trans. N.Z. Inst., vol. 49, pp. 36.5-92, 1917. 



§ R. Speight, An Ancient Buried Forest near Ricarton, Trans. N.Z. Inst., vol. 49, pp. 

 361-64, 1917.' 



II R. Speight, A Preliminary Account of the Geological Features of the Christchurch 

 Artesian Area, Trans. N.Z. Imt.', vol. 43, pp. 420-36, 1911. 



Tf R. Speight, A Preliminary Account of the Lower Waipara Gorge, Trans. N.Z. Imt., vol. 

 44, pp. 221-33, 1912. . . . ' . Structural and Glacial Features of the Hurunui Valley, loc. 

 cit. supra. 



** J. A. Thomson, Coal Prospects of the Waimate District, South Canterbury, Eighth Ann. 



Rep. of the Geol. Surrey Branch, N.Z. Pari. Paper C. — 2, pp. 158-62, 1914 Jlineral 



Prospects of the Maharahara District, Hawke's Bay, ihid., pp. 162-70, 1914 



The Geology of the Middle Clarence and Ure Valleys, East Marlborough, New Zealand, Trans. 



N.Z. Inst.,' vol. 51, pp. 289-349, 1919 The Notocene Geology of the Middle 



Waipara and Weka Pass District, North Canterbury, New Zealand, Trans. N.Z. Inst., vol. 52, 

 pp. 322-415, 1920.) 



