C—2b

A few minor corrugations were seen by the writer in the steeply dipping limestone of the Puhipuhi Valley about four miles from the Hapuku River. Though Grey Marl appears not far away, the writer's notes are insufficient to enable him to say whether the corrugated rock forms part of tin- upper limestone (Weka Pass Stone horizon) or of the underlying Amuri limestone. Marshall, Speight, and Cotton describe corrugation or puckering of the Amuri limestone at the mouth of Okariki (Okarahia) Stream, near Amuri South Bluff (J 9. p. 390), whilst yon llaast and Button mention what appears to be similar corrugation of the Amuri limestone on the south bank of the Conway River, fen or twelve miles from its mouth (2, p. 40 j 9, p. 271). Unconformities. References io the presence of two unconformities above the Amuri limestone have already beeu made, and the evidence for their existence will now be presented in detail. The lower of these unconformities, that separating the Amuri limestone proper from wfiat may be called the upper limestone (horizon of Weka Pass stone) has apparently noi previously been definitely recognized as a stratigraphical break.* The chief evidence in its favour is furnished by the water-worn and irregular upper surface of the Amuri limestone, similar to that at Weka Pass as described by Hutton (4, p. 44), and by the presence of the thin bed of phosphatized limestone conglomerate previously mentioned. The pebbles of this rock weather externally to a darkgreenish hue, and as a rule their interior is also more or less greenish in colour. This peculiarity explains Hector's description of (In- bed in question as "a thin layer of brecciated fragments of calcareous greensands " (3, p. xi). Thus he does not recognize it as a conglomerate or as evidence of unconformity, and in this is followed by McKay. Hutton speaks of bands! of conglomerate interbedded with the Amuri limestone at Kaikoura (4, p. oil), but, curiously enough, does not suspect the existence of a stratigraphical hiatus. Owing to the presence of phosphate in tho horizon under discussion, the question of unconformity has direct economic as well as scientific importance, and therefore a full summary of the writer's notes respecting the contact; between the Amuri and the upper limestone will be given. Immediately east, of the Maori village on the south side of Kaikoura Peninsula a considerable exposure of limestone above high-water mark is visible. Here the conglomerate layer, which will be found some chains west of the Grey Marl outcrop, is 6 in. thick, and consists mainly of subangular pieces of phosphatic limestone, with an average diameter of !l in. or a little more. The rock above is white flaggy limestone, that below is a greyish-white argillaceous limestone, the uppermost layer of which is crowded with'" fucoid " casts, There is no detectable discordance in the bedding-planes, of the over- and the under-lying rock. In the cliff a few chains to the north the conglomerate, here about 5 in. thick-, may he found after a little search in a horizon roughly 120 ft. or 130 ft. below the Grey Marl. On following the shore-line eastward from the Maori village the conglomerate is next seen about a mile away at the base of a small headland north-east of Atui Point, where it is 6 in. to Din. thick. Here it is underlain by 6 in. of limestone containing a few scattered pebbles of calcareous rock and some small irregular lenses of sandstone, which appear to represent wormcasts. Below this is a band of limestone, barely 1 ft. thick, which also contains cylindrical worm-casts approaching in their character so-called fucoid easts. Above the conglomerate is 2 in. to 3 in. greensand, followed by some feet of more or less glauconitie limestone containing a few pebbles of the same kind of rock (probably somewhat phosphatized)! The conglomerate itself consists of small subangular to rounded calcareous pebbles with greenish exterior, embedded in a matrix of calcareous green sand. Its strongly phosphatic character is shown by the following part analysis: Calcium carbonate (CaCO 3 ), 34-95 per cent; phosphoric anhydride (I' 2 O r> ) 24-55 per cent. The phosphoric anhydride is equivalent to 5362 per cent, of tricalcic phosphate. The phosphatic conglomerate can be traced some distance along the cliff to the north-east in a horizon 60 ft. to 70 ft. below the, Grey Marl. At one point in the cliff 2 ft. of greensand with interlaminated limestone overlies, but more to the north-east this almost completely disappears. ' As viewed from a little distance tho limestone above and below it are very much.alike. Owing to faulting the conglomerate a little to the northward is raised to a horizon above the cliff-top, and therefore cannot be seen for some distance, but is again visible at a small headland not far from the east head of the peninsula. Here it, is 9 in. thipk, and overlain by 2 in. or 3 in. of greensand, above which comes 50 ft. or 60 ft. of limestone and then the Grey Marl. The contact between the upper limestone and the Grey Marl is in several respects very similar to that just described. It may best be seen on the rock shelves at the east head of the peninsula and near the Maori settlement. In both localities there is a sharp passage from limestone to a calcareous grey sandstone, which in places near the contact is somewhat, coarse-grained. On the whole tho sandstone has been deposited parallel to the bedding-planes of the limestone, and therefore there is apparent conformity. As explained previously, the discrepancy produced by local corrugation of the limestone has no bearing on the question of unconformity, but at one spot near the Maori village there is apparently a very slight angular unconformity, which, owing to faulting, cannot be clearly traced for more than a few yards. Viewed closely, the upper surface of the limestone is highly irregular and covered with small erosion hollows, now tightly filled by the overlying calcareous sandstone, which, coloured somewhat by glauconite, also penetrates into small irregular passages and fissures in the limestone. Many of the smaller passages are undoubtedly worm-borings, but owing to extensive reboring in modern times and just prior to the last minor uplift of the land this is not so prominent as it would otherwise be. At one or two places the limestone close to the contact is

* Button's unconformity in the Kaikoura Peninsula is at the base of the Grey Marl (see poslea). f There is, however, only one conglomerate horizon in the limestone.

22