Overview
Sat. Feb. 14.
Took photo (87) 1/4pl.[ate] of Mr Sarcich in wagonette at stable yard + (88) Ditto on Extension Road. Also (89)1/2pl. of Mr Stubbs house showing the use of shore boulders in architecture. Caught the 10.45 train to
Pukerura + on arrival re-examined the sands + yards of Supposed Tertiary age. Followed the skyline along the curves going north. The sky cuttings are all through the sand strata, but the low ridge immediately east of Pukerura + across which the sky passes in a cutting has a core of weathered greywacke +c. capped by the sand beds. The Tertiary strata continues along the line of the sky to within a few chains.[Page break]
of the 23 mile py, + appears to form the lower part of the spurs + penetrate into the gullies to the east of the skyline. There is evidence that, whatever their age + origin, the sand + gravel strata we laid down on area of considerable relief. Descended a small gully into
Pukerura Bay + walked to the north of the large ravine explored last Tuesday. Drew a section of the beach, cliff + flat top above to the head of the larger of the two incipient gullies or "washouts" + also noted the contour of the stream drawing their trunk ravine. At the mouth of the ravine the nearby Horizontal Tertiary beds can be seen resting on the upturned edges of the Jura-Triassic strata (weathered greywacke, struck apparently NE, SW), the line of the junction northwardat an angle of 6" - photo (90] 1/4 pl.[ate] of this junction, also made a sketch section. Re-examined the strata in the ravine + in the larger of two young gullies - photo (91) 1/4pl. looking down the young gully from head; the beds dep[th] at an angle of 2" but the near mouth of the large ravine the dep of the sand-gravel strata varies, in the same section, from 0" to 2". The complete sequence + thickness of the strata cannot be clearly determined: (1) on account of the slipped debris; (2) because of frequent variations
in the texture + character of the strata.[Page break]
In a general way the bedding is practically horizontal but in detail in many places it is irregular, sands changing into gravels and lenticular patches of either occurring within the other material. The succession given in the above table is however substantially correct. The gravels are often cemented by iron compounds into a conglomerate or breccia which increase in coherence towards the base of the series where there is a hard conglomerate immediately above the old basement strata + large solid blocks of this conglomerate encumber the bed of the stream into the ravine at its lowest end just before it cascades down to the beach. This distinct Jura-Triassic-Tertiary junction mentioned above does not continue upstream with the same regularity, there being a distinct rise in the greywacke floor. After a spell on the beach climbed to the top of the cliff just east of Pukerura Pt + ascended to crest of ridge of hills above (the coastal ridge), visiting the trig stns [stations] No.1 + No.2 on a map. For general topo. from this point see notebook. To my surprise I found a patch of the ripple-marked sands on the south side of trig No.1 + only a few feet below the summit. It would thus seem that the Tertiary beds at one time completely covered all this country + that the main level
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below, i.e. at Pukerura Saddle + north + south of this point, is, if my recent theory of subsidence is correct, part of the original high level subsided veg[etation], a sunk-land strip. Lower level surfaces of the Tertiary beds are probably erosion levels indicating successive (partial) erosion cycles. The presence of the sand-gravel strata on the watersheds of the present drainage systems + also the existence in these strata of at least two successive (partial) erosion cycles (the present + a preceding one), show that the strata referred to are not the deposits of the existing streams, + must therefore be of considerable age, ie at least Late Tertiary. My first impressions are thus confirmed. The resemblance of some of the beds of these Tertiaries to the Horowhenua sand-stone appears to be due to the fact that both are the waste (at different periods) of the same formation i.e. the Jura-Triassic. The main differences between the Horowhenua sandstone and the Pukerura sands are the greater coherence, the coarser texture + the distinctive regular lamination of the former. Unlike the Pukerura sands, the Horo sandstone, under sublateral wastage does not give rise to sand-drifts being apparently too coherent + coarse-textured. Descended from trig No.2 by a spur forming the hillside divide between
[Page break]Tapu Creek + the ravine draining to Pukerura Bay. At the eastern foot of the coastal ridge is the gently eastward-sloping peneplain surface noted in a similar position further south. Pukerura saddle is a splendid example of an indistinct divide - only a smooth flat surface separates the sources of Tapu Creek + those of the ravine draining to Pukerura bay; the head streams are only incised a few feet below the flat surface + their channels are fairly broad + open. As it was too early to get a tram back I returned home on foot via the sky line and "sledge track" The rly[railway] cuttings as far as the 20 mile peg are cut through the Pukerura series, the sand beds predominating, but here + there are gravely strata (sometimes in irregular lenticules. The streams from the coastal ridge have trenched the peneplain surface + in some cases there is a second flat surface or wide terrace at the lower level within a stream-trench + this in turn has been cut by the present v-shaped channel of the stream - both flat surfaces appear to be "cut" surfaces. The gravel beds of the Pukerura series are well exposed below the level of the railway line just north of the 20 mile peg in the deeper stream trenches. South of the 20 mile peg the greywacke strata reappears + is for
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a short distance capped by the sands of the Pukerura series. On ascending the northern end of the ‘sledge track’ I found another patch of the Tertiary sands, so it is clear that they formerly had an extensive range both vertically + horizontally. Soon after I reached home, we all including Doris party went down to the 5:15 p.m. train to see father + Clara who were passing through on their way home. Father not looking to well on account of an abscess on a tooth from which he has been suffering lately.