Thomson. — Geology of Middle Clarence (ind Ure Valleys. 311 



At the north-eastern end the structure becomes complex. There is 

 a large area of down-faulted Notocene rocks between tlie Isolated Hill 

 Creek, the upper Nidd, and the eastern side of Whernside. The limestone 

 of Whernside is continuous with that of Benmore by a narrow strip, and 

 presents a steep scarp to the Benmore Stream, where it probably rests 

 conformably on Clarentian rocks. Along its north-western boundary it is 

 probably faulted against the middle or upper Clarentian. The main mono- 

 clinal ridge of Amuri limestone passes from the Chalk Range and Brian 

 Boru in a great curve to Benmore, but the outcrop of the Clarentian rocks is 

 divided mto two parts by the infaulted limestone of Whernside. The upper 

 Clarentian beds outcrop under the limestone on the same curve, finally 

 feathering out in the upper part of the Isolated Hill Creek. The lower 

 beds cross the upper Wharf into the watershed of the Kekerangu River, 

 where the whole series is presumably again resumed in the Front Ranges. 



Discontinuous strips of Notocene rocks are involved along a second fault, 

 which we may call the Quail Flat fault, running from the Gore River to 

 the mouth of the Herring River, thence approximately along the Clarence 

 River past Quail Flat, and ending on the north-west side of Red Hill. 

 Between the Gore River and the Herring River all beds up to the Weka 

 Pass stone are involved at river-level, and in the Herring River the width 

 of the outcrop is extended by well-marked folding for some miles to 

 the south-east of the fault-line, l)ut farther to the north-east only dis- 

 continuous strips of the lower Clarentian rocks are preserved. There is 

 evidently along this line strong longitudinal w^arping of the base of the 

 Notocene, equal to nearly the whole thickness of the series, besides 

 transverse folding. 



A third small strip of lower Clarentian rocks only is involved in another 

 parallel fault, which crosses the Herring River several miles above its mouth. 

 This fault has not been traced on either side of the river. McKay (1887, 

 p. 104) mentions the existence of two other " outlying patches " of Clarentian 

 rocks, the one east of Gridiron Hill, the other one and a half miles to two 

 miles east of Limestone Hill, but whether these are involved along the 

 same or still another fault-line or are simple outliers is not known. 



The large outcrop of Notocene rocks which extends from Bluff Hill 

 across the Clarence River (below the junction of the Bluff River) to beyond 

 Limestone Hill has not been satisfactorily explored. It is apparentlv not 

 involved along a fault-line, but seems to constitute an outlier preserved by 

 a synclinal depression west of the great Clarence and Quail Flat faults. 

 The Notocene here attains its greatest elevation, rising to 4,231 ft. in 

 Limestone Hill.* 



In the detailed descriptions following it will be convenient to treat 

 separately the Clarentian, the Amuri limestone and Weka Pass stone, the 

 ■' grey marls," and the great Marlborough conglomerate. 



The Clarentian Bock-s. 



The Clarentian as defined by me in 1917 comprises all those Notocene 

 rocks in the Middle Clarence Valley lying below the flint-beds at the base 

 of the Amuri limestone. In the neighbourhood of Coverham fossils have 



* There are at least three mountains in the Clarence Valley to which this name 

 has been given — one in the Upper Swale Valley, one between the Mead and Dee Gorges, 

 and one on the south-east side of the Clarence River, above the junction of the Bluff 

 River. It is the last that is here referred to. 



