98 Transactions. 



as well, but I have found no appearance of limestone, which is so well de- 

 veloped in the Waikari district to the south-west. Limestone does occur 

 in the upper part of the Scargill Valley, in the form of faulted strips, but I 

 have not traced it farther towards the Hurunui. The beds have a general 

 north-east strike, and a dip to the south-east of from 15° to 20°. Where 

 the beds cut across the Hurunui. which they do at an angle of about 45°, 

 they are disturbed from their proper dip and are pulled up along the line 

 of a fault on the downthrow side till they are nearly vertical ; but this 

 disturbance does not extend far from the fault-line, and may be attributed 

 entirely to the movements caused by it. The result is that the beds form 

 a strip running along the north-west side of the Waikari-Kaiwara de- 

 pression, with slope accordant to that of the underlying surface, and if 

 they were removed a characteristic " stripped surface," as described by 

 Thomson,* would be disclosed. I do not know what special name has 

 been applied to valleys of this form, except that I think the term " basin 

 range valley " has been applied to somewhat similar valleys in the western 

 United States ; but the Waikari Valley is of a somewhat different type, 

 and also the name just cited is an unfortunate conjunction of terms. The 

 name " rift valley " does not apply, because such are determined by faulting 

 running along two sides, whereas these under consideration are attributable 

 to tilting which has accompanied faulting along one line only. I suggest 

 the name tilted strip as being a suitable name in case none has been 

 already applied. 



The most remarkable feature of the course of the Hurunui is its con- 

 tinuance across this depression without any apparent effect on its course. 

 Although the earth-movements accompanying the faulting must have been 

 of fairly recent date, the river has maintained its original course. It is 

 interesting to compare this case with that of the Clarence Valley, farther 

 north, where a similar valley caused by faulting on a much larger scale 

 has dominated the course of the river. In the case of the Hurunui the 

 movement must have been slow, and some cause must have been present 

 which enabled the river to reach a lower base-level almost as fast as the 

 downward movement occurred in the beds in this portion of its course. 

 This cause will be evident from a consideration of the features of the next 

 compartment into which the river-valley has been divided. 



(4.) The Greta-Cheviot Basin. 

 The greywacke gorge of the river continues for about three miles below 

 the Ethelton Station, when the valley opens out and the river has a wide 

 shingly bed with flanking terraces cut in the marls of the Motunau or 

 Greta series. Soon after its emergence from the gorge it receives the small 

 Greta Creek, which occupies a valley similar in form and origin to that of the 

 Waikari and Kaiwara. The beds let down by the fault which determines 

 this valley develop northward into those of the true Cheviot basin, which 

 is some five miles across, and extends past the Cheviot township across 

 the Waiau as far as the Conway River. The structure of this basin is 

 dominantly synclinal. The beds exposed on the floor of the basin are 

 clays, sandy clays, sands, &c, of Mio-Pliocene age, passing down conform- 

 ably into calcareous oreensands (= Weka Pass stone) and hard limestone 

 (= Amuri limestone). The limestone is exposed in places along the western 

 edge of the greywacke ridge which separates the basin from the sea, and 

 through which the Jed has cut its gorge. On the seaward side of this grey- 



* J. A. Thomson, Coal Prospects of the Waimate District, South Canterbury, N.Z. 

 Geol. Survey. 8th Aim. Rep., p. 1(50, 1914. 



