THE GREAT MARLBOROUGH CONGLOMERATE 



357 



are the bowlders regarded by McKay as exotic, but Thomson' 

 refers them to the same source as the possibly derived masses in the 

 Grey Marl in this locality); Amuri Limestone, not very abun- 

 dant, in blocks up to 6 ins. in diameter, but rarely larger; sand- 

 stone blocks of all sizes, some resembling the sandstones of the 

 Cretaceous, others possibly pre-Cretaceous; pre-Cretaceous or 

 "Maitai" pebbles, both graywacke and jasperoid, forming, as 

 already mentioned, the bulk of the finer material. Fig. 6 is a 

 photograph showing the general appear- 

 ance of the conglomerate in the Mead 

 section. In the Mead and Dee sec- 

 tions, as well as elsewhere, thin bands 

 of sandstone occur throughout the con- 

 glomerate. They are referred to in the 

 next paragraph. 



FLUVIATILE ORIGIN 



%< l?^% 



Fig. 6. — The conglomerate 

 in the gorge of the Mead. 

 (The hammer handle is lo 

 inches long.) 



From the foregoing descriptions and 

 from those quoted, as well as from the 

 photographs of the conglomerate out- 

 crops at Heaver's Creek, Kekerangu, 

 and Kekerangu South Head pubhshed 

 by Park,"* it will be gathered that su- 

 perficially the material resembles glacial 



morainic accumulations. Park^ lays stress on the angular nature 

 of some of the bowlders, but no polished or striated bowlders 

 have as yet been described. "Large angular blocks" are certainly 

 present, but it is also true that everywhere the bulk of the con- 

 glomerate consists of medium-sized to small pebbles of hard rocks, 

 exceptionally well rounded. This fact was noted by McKay.'* 

 There is, moreover, almost everywhere a rough sorting into coarser 



' J. Allan Thomson, N.Z. Geol. Surv., -jth Ann. Rep., p. 123, 1913. 

 ^ J. Park, Trans. N.Z. Inst., XLIII, Pis. 20, 22, 1910; Geology of New Zealand, 

 Fig. 93, 1910- 



3 J. Park, "Marlborough Coastal Moraines," Trans. N.Z. Inst., XLIII, 522, 1910. 

 ^ See, for example, op. cit. {1886), p. 115; ibid. {1892), p. 4. 



