OF THE " "WEKA-PASS STONE OF NEW ZEALAND. 



271 



" which," he sa3's, " must convince any one that the conformity to 

 the Mount-Brown beds in the south-west branch of the Motunan 

 River is only apparent." I confess that I cannot follow this 

 reasoning. It seems to me that these sections, if they are correctlj^ 

 interpreted, show an unconformity between the Amuri limestone 

 and the lower beds of the Waipara Sj'stem, and a regular sequence 

 from the Amuri limestone into the Mount-Brown beds, although 

 the WeJca-joass Stone is ahseyit. But probably Mr. M'Kay has here 

 mistaken the Weka-pass Stone for the Amuri limestone, a very easy 

 mistake to make ; and if this is the case his sections will agree with 

 those in other localities, 



Stonyhurst. — This place is on the sea-coast, a little south of the 

 mouth of the Hurinui. Here the Amuri limestone is overlain by a 

 grey sandstone, probably the representative of the Weka-pass Stone. 

 Between the two rocks is a bed of conglomerate formed by sub- 

 angular pebbles of slate. At first sight all three appear to belong 

 to one system ; but a close inspection shows that the surface of the 

 limestone is fissured, and that the sandstone penetrates through the 

 conglomerate into the fissures of the limestone. This, however, may 

 be due to chemical erosion. 



Biver Coniuay. — Some ten or twelve miles from the mouth we 

 again get an excellent section in the bed of the river (fig. 4). Here 



S.S.E. 



Fig. 4. — On the South Bank of the Coniuay Biver. 

 (Distance | mile.) 



N.N.W. 



For explanation see fig. 1. 



the Amuri limestone is seen to be somewhat folded, and overlain 

 quite unconformably by a bed of blue marl passing upwards into 

 pale yellow sandstone *. As will be seen later, the fossils found 

 in this marl make its age rather doubtful. I believe it to be 

 the same as the Grey Marl of the Weka Pass, but it may be younger. 

 Dr. von Haast says of this section, " The lowest limestone layers have 

 been deposited without disturbance, but seem afterwards, on the 

 western side, to have been folded up in a most remarkable manner, 

 after which newer beds of the same rock have again been deposited, 

 reposing unconformably upon the lower beds. This fold does not 

 occur on the opposite, eastern, side, but the unconformity between 

 the upper and lower beds exists there also " f. The fossils, how- 

 ever, show that the upper rocks are mUch younger than the Amuri 



* 'Geological Reports,' 1873-74, p. 48. 

 t ' Geological Eeports,' 1870-71, p. 40. 



