Speight. — Tht Older Gravels of Norih Caiittrhury. 279 



involved in anticlines and synclines, and sometimes dip at steep angles — 

 as hioh as 55° to 60°. They do not contain, as far as my observation goes, 

 any limestone-fragments such as might have been shed from the Weka Pass 

 or Amuri limestone beds, and this suggests that they are not unconformable 

 to the beds containing those limestones, a conclusion which is supported 

 by general stratigraphical evidence. These Motunau beds are capped 

 unconformably by gravels containing numerous fragments of limestone, 

 and from their lack of distinct stratification it may be concluded that they 

 are high-level terrace-gravels of more recent date. Similar gravels occur 

 on the downs just east of the Amberley-Waipara Railway, covering a con- 

 siderable extent of country, as they are occasionally exposed in the sides 

 of deep washouts and cap the cliffs cut by the river in making its gorge. 



Along the north bank of the river below the Teviotdale Bridge there is 

 also a series of Motunau beds, consisting of sands, sandy clays, and gravels, 

 some of which are very fine and smooth and are evidently of marine origin. 

 These beds contain fossil shells at various levels, which point to the age 

 being Mio-Pliocene or Pliocene (Speight, 1914). On the south bank of 

 the river the beds are much obscured by slip-material and vegetation, so 

 that in no place is the contact clearly displayed. On the terrace near the 

 mouth of the river the following section is exposed : — 



1. Yellowish sands, exposed at river-level and for 6 ft. upwards. 



2. Sandy lignite, with well-marked woody structure and containing 



crystals of gypsum in stellate and columnar groups, 4 ft. in 

 thickness. 



3. Sandy clay (fireclay ?), with occasional pieces of bituminized wood. 



4. Lignite, full of bituminized wood, 6-8 in. 



5. Sand and sandy clay, with pieces of wood, 4 ft. 



6. Gravel, 6 ft. 



7. Sandy clay. 



8. Gravel. 



Farther up-stream the lignite-beds are exposed in similar stratigraphical 

 position, succeeded by yellowish clays and sandy gravels, and at one place 

 there is an exposure under the lignite of well-stratified and rounded marine 

 shingle. 



These beds all strike east-south-east and dip west-south-west at very 

 flat angles, and it is impossible to tell on stratigraphical grounds whether 

 the gravels overlying the lignites are conformable or not, or whether they 

 belong to the Kowai series or to recent terrace-gravels. The locality 

 furnishes evidence of the ease with which conformity may be simulated 

 under certain circumstances. If level beds are planed by the sea, and no 

 irregularity left on their being depressed and covered with a veneer of sedi- 

 ments, apparent conformity may occur over considerable distances, and 

 especially will this be the case if the beds in contact are of a sandy or 

 gravelly nature. A suggestion of unconformity is given in this case by 

 the presence in the lowest layer of gravel of large pebbles, up to 8 in. in 

 diameter, and more or less subangular, indicating strong currents on a land- 

 surface or on a sea-bottom in close proximity to land, and that the beds 

 were deposited under conditions entirely dissimilar from those obtaining 

 when the better-rounded gravels were laid down. 



Other Canterbury Localities. 

 There are other localities in this part of the South Island where similar 

 gravels occur, among which may be cited the Isolated Hills in the Culverden 



