354 Transactions. 



detailed descriptions by Morgan (1915, 1916) and tlie exhaustive discussion 

 by Speight and Wild (1918). The upper beds of the Amuri limestone are 

 not compact, but consist of small separated blocks of white limestone, a few 

 inches in diameter, in the interstices of which there occurs a filling of 

 calcareous greensand of the same nature as the overlying bed of greensand. 

 The upper 1 ft. or 2 ft. are most affected, but the penetration of the lime- 

 stone by the greensand occasionally reaches a depth of 6 ft. The blocks of 

 limestone are mostly irregular in outline, and similar in shape to the cuboidal 

 blocks isolated by jointing throughout the limestone. Morgan describes 

 the fissures between the blocks as irregular cavities, following joint- 

 planes to a great extent, but evidently enlarged by chemical erosion or 

 solution, and mentions the existence of small peninsulas of limestone, some 

 of which are joined only by a narrow neck to the main mass, extending 

 several inches upward into the glauconitic sandstone. Speight and Wild 

 describe the Amuri limestone as " jointed into flaky quadrangular blocks, 

 the upper 2 ft. or more being bored by marine worms and the casts filled 

 with glauconitic sandstone. The amount of boring increases progressive!}'- 

 upwards until what may be called the transitional layer is reached." When 

 I first examined the contact, in 1912, I noted occasional borings with 

 round sections in the limestone, filled with glauconitic calcareous sandstone, 

 but I formed the impression that the greater part of the penetration of the 

 limestone by the greensand had taken place along joint-planes enlarged 

 by solution, and after re-examining the contact with Speight and Wild's 

 explanation in mind I am still of the same opinion, and agree with Morgan. 

 I noted also in the gorge of the Weka Pass Stream above the viaduct that 

 5 ft. below the contact, where the limestone is practically undisturbed, there 

 are occasionally bedded lenticular masses of glauconitic calcareous sandstone 

 within the limestone. Speight and Wild observed a similar phenomenon in 

 the Weka Cireek, where they describe the limestone as breaking into quad- 

 rangular blocks, with interstitial calcareous greensand in layers parallel to 

 the bedding in its upper portions, very occasional burrows extending to 6 ft. 

 below the actual junction. 



The uppermost part of the Amuri limestone, termed by Speight and Wild 

 the " transitional layer," they describe as follows : " This consists in its 

 lower part of Amuri limestone material thoroughly bored, with the interstices 

 filled with glauconitic limestone. The result of the boring increases progres 

 sively, and the quantity of glauconitic material increases ^mr* passu. The 

 upper 6 in. is completely bored, so that peninsulas of Amuri liinestone 

 project at times into the overlying glauconitic layer, and at times become 

 detached and resemble subangular pebbles in appearance. They are more 

 phosphatic than the underlying limestones, and the included glauconitic 

 limestone is more phosphatic than the overlying glauconitic layer. Included 

 in this band are small angular nodules, green or black in colour, which 

 are strongly phosphatic. Very occasionally small well-rounded pebbles of 

 quartz, about ^ in. in diameter, are met with." 



The lowest layer of the greensand, described in the last part of the above 

 extract, is termed by Speight and Wild the '' nodular layer." The great 

 majority of the inclusions are vSubangular pieces of Amuri limestone, slightly 

 phosphatized, and the true phosphatic concretions are relatively scarce and 

 quite small. The limestone inclusions are most abundant in the lower 12 in. 

 of the greensand, but occur sporadically up to 2 ft. from the base, and are 

 then, according to Morgan, mostly rounded. In addition to the quartz 

 pebbles noted in the Weka Pass, Speight and Wild record a well-rounded 



