Speight. — The Older Gravels of North Canterhurij. 275 



Farther down-stream the beds lie almost flat, with an east-south-east strike 

 and a dip to the north-north-east at very low angles (less than 5°). On a high 

 bluff a series of well-stratified sands and sandy gravels is exposed. Near 

 the base of the cliff, under a sandy bed cemented in its lower part with iron 

 oxide, lies a narrow band of sandy carbonaceous shale, 6 in. to 8 in. thick, 

 containing pieces of lignified wood, and passing down into sandy clay with 

 interstratified irregular lenses of lignite. Under these lie sands and sandy 

 gravels, and then bluish-green and brown sands. A little below this the 

 strike swings round to north-north-east, with an easterly dip, and in a narrow 

 gidly on the south side of the stream an interesting section is exposed. Here 

 both the bluish-green sands and the sandy gravels have been eroded, and 

 on the eroded surface have been deposited sands and sandy gravels contain- 

 ing fragments of the lower beds. A similar occurrence is to be observed on 

 the face of a cliff' in the main stream, the lower beds dipping 10° and the 

 upper lying flat across them. A thin layer of broken-shell fragments was 

 observed high up on the face of the cliff in an inaccessible position. 



Higher in the series are rapidly alternating sands and fine sandy gravels, 

 in layers down to 1 in. in thickness, and these are succeeded bv sands, sandy- 

 gravel beds, and bluish-grey and brown sands, the former with broken-shell 

 layers. In the gravels are numerous fragments of limestone, which must have 

 been derived from a surface of the Amuri limestone exposed to decided erosion. 

 The fragments are generally less than 2 in. in length, but are sometimes 

 longer, and are usually flattened like beach shingle. There is no doubt as 

 to the interstratification of these beds in the series under consideration, as 

 the same feature was observed in a deep gully to the north of the stream in 

 its proper stratigraphical position. The presence of these fragments is posi- 

 tive proof of the presence of an unconformity between these beds and the 

 Amuri limestone, and supports the stratigraphical evidence from the Grey 

 River. In the bluish-green sands there are occasional shell-fragments. 



For some distance below this spot there are no clear sections, but sand is 

 probably the major constituent of the beds. At the junction with the Kowai 

 River, however, there are high cliff's on the northern side, where the strata 

 are clearly visible for half a mile. The lowest beds exposed in this locality 

 are sands with interstratified gravels, in which limestone-fragments form a 

 most important constituent. The beds with the limestone-fragments are at 

 least 50 ft. thick, and may be thicker. Higher up the limestone constituent 

 gets less and less, and the pebbles are entirely of greywacke. No other 

 included material, such as fragments of Mount Brown limestone, was noted 

 at this spot, which might indicate the date of the break between the Amuri 

 limestone beds and those under consideration. It is possible that these 

 gravel beds are unconformable to the greenish marine sands, since for some 

 distance no exposures are visible which enable their relations to be precisely 

 determined, and there is evidence from other parts of the area that these 

 upper gravels are unconformable to greenish sands — e.g., in the Grey River 

 (see p. 272) and also in No. 2 Creek (see p. 276). These gravel beds are 

 fairly well stratified, with occasional beds of sandy clay and thin carbonaceous 

 shales, their total thickness being about 1,000 ft., and the whole thickness 

 of the series from the junction of the Mount Brown beds upward being about 

 1,500 ft., though this may include two series — viz., the Motunau and the 

 Kowai series. 



The course of the main stream above its junction with the tributary follows 

 almost along the strike of the beds, so that the structure is not so well 

 displayed. The beds exposed consist of marine sands, which are remarkablv 



