356 Transactions. 



tertiaria, Aturia ziczac var. australis, Lima laevigata, Peden wilUamsoni, 

 P. fischeri, P. heethami var. B ; beside brachiopods, ecliinoids, corals, and 

 sharks' teetb, in which Hutton's identifications cannot be so safely accepted. 

 Unfortmiately, many of the older collections in the Canterbury Museum are 

 labelled simply " Weka Pass," without reference to the exact horizon. It is 

 possible that the species he identified as Lima laevigata should be L. imitafa, 

 which resembles it in size. 



The Weka Pass stone presents little variation in composition and thick- 

 ness throughout the district. Morgan estimates it at 100 ft. thick in the 

 Weka Pass Stream. Usually it is not so thick, the average being perhaps 

 60 ft. It succeeds the Amuri limestone everywhere this is developed, 

 but in the tributaries of the Omihi Creek east of Mount Donald it overlaps 

 the Amuri limestone and rests directly on the greywackes of the Moore's 

 Hills block. No actual exposure of the junction can be seen, but there 

 is a small, flat-lying outlier lying off the second V outcrop uphill east of 

 Moimt Donald, and near the top of a road leading from the Waikare Valley, 

 ■which approaches within 20 yards of an outcrop of greywackes, with only 

 a few feet difference in level, so that not more than 20 ft. of beds can 

 separate the two rocks. The neighbouring greywacke surface has all the 

 characters of a recently stripped fossil peneplain. The Weka Pass stone 

 in this neighbourhood is more glauconitic than usual, with fairly numerous 

 dark phosphatic concretions, and has a peculiar pencil-like or thumb-like 

 fracture. 



The " Grey Marls " and Mount Brown Beds. 



The beds following the Weka Pass stone have long been known as the 

 ■' grey marls " and the Mount Brown beds, and the conformity or uncon- 

 formity of these two sets of beds has been much canvassed, but there 

 has been no close definition of what is to be included in these two series. 

 " Grey marls " by common consent include any mudstone between the 

 Weka Pass stone and the overlying limestones, which also by common 

 consent are included in the Momit Brown beds ; but between these two 

 limits there is also a considerable thickness of sands and sandstones ; and, 

 moreover the upper limit-— viz., the lowest Limestone of the Mount Brown 

 series — is not a persistent lithological horizon in the district. It will there- 

 fore be convenient to describe these two " series " together. 



Five limestones must be distinguished in the Mount Brown series, and 

 may be conveniently indicated by the letters A, B, C, D, and E. The 

 lowest. A, forms a cuesta on the Ram Paddock, and also on the watershed 

 between Boby's Creek and the Kowhai River, towards Mount Grey. It 

 is a white polyzoan impure limestone containing in places an abundance of 

 large cup-shaped Polyzoa, and is the " white and yellowish calcareous sand- 

 stone " of Hector (1869), and the " Bryozoa beds " of Haast (1871). The 

 succeeding limestones, except the last, are mostly reddish-brown rubbly 

 arenaceous limestones, the calcareous matter being largely comminuted 

 shells of various marine organisms. Polyzoa, barnacles, or brachiopods in 

 places constitute the greater part of the limestones, and there are also 

 molluscan shell-beds. The second, B, forms the lower of the two limestone 

 cuestas on the south-east side of the ^eka Pass, and contains few fossils 

 except small cup-shaped Polyzoa and barnacles. It may possibly be the 

 same as the third, C, which forms the lower 'band on the cliffs overlooking 

 the Waipara River below the limestone gorge, and is characterized by 

 the presence of the brachiopod Magadina waiparensis Thomson. The 

 fourth, D, is the main band throughout the district, occupying the 



