HuTTON. — Geology of the Trelissick Basin. 401 



and these are represented in the Trehssick Basin by the upper 

 limestone which forms Castle Hill. 



The correlation of the Waipara System with any European 

 equivalent at present presents considerable difficulties. The 

 occurrence of Plesiosaurns above beds containing leaves of 

 dicotyledonous angiosperms would seem to indicate an upper 

 cretaceous age ; but Mt/Hobatis (which is here thought to be on 

 the same horizon as Plesiosaurns) has never yet been found in 

 the Northern Hemisphere in any mesozoic rock. I have often 

 protested against the cretaceo-tertiary formation as defined by 

 the Geological Survey ; but this has been, not because I deny 

 the possibility of the Waipara period extending into the tertiary 

 era, but because I deny that the limestones, etc., of Weka Pass, 

 Ototara, and other places belong to the Waipara System. 



Oamaru System. 



Sedimentary Rocks. — These rocks attain their greatest eleva- 

 tion at Flock Hill (3,269 feet). At Castle Hill they go to 3,023 

 feet, and at Prebble Hill to 2,959 feet. 



In the upper part of Coleridge Creek, tuffs, covered by lime- 

 stone, rest on the rocks of the Waipara System, and dip 55° 

 N.N.W. To the west an apparently isolated portion of the 

 limestone requires further examination, as it appears to rest on 

 Pareora beds ; but probably this is deceptive. To the eastward 

 the beds curve round to the north, and the limestone rests on 

 the palaeozoic rocks ; they then again cross the creek, dipping 

 at a high angle to the west. This is a famous locality for 

 fossils, the tuffs under the limestone containing numerous teeth 

 of Lamna, Carchn radon, and Sparnodus. On the north side of 

 the creek the limestone is absent, the Pareora rocks res^ting on 

 the tuffs. In White-water Creek the limestone is about 40 feet 

 thick, and dips 15° W.S.W. It is underlain by a bed of con- 

 glomerate, formed of rounded fragments of volcanic rocks and 

 limestone in a calcareous cement, which is full of fossils ; below 

 it comes dark-green tufaceous sandstone. The limestone can 

 be followed continuously from here northward to Castle Hill, 

 where it is cut off by the fault already mentioned. Between 

 White-water Creek and Castle Hill the dip is 8° W. to 12° W. 

 At Castle Hill it is 25° W.N.W., and near the fault 32° N. The 

 eastern slope of Castle Hill I did not examine sufficiently ; pos- 

 sibly the Waipara System may form the lower part. The lime- 

 stone at Castle Hill is not less than 100 feet thick. 



The Oamaru System again appears on the north side of the 

 first limestone gorge of the Porter Eiver, dipping 33° N.W. 

 The greensands are here about 40 feet thick, but the limestone 

 is very poorly developed, having been largely denuded before the 

 deposition of the Pareora System. At the junction of the 

 Thomas Eiver with the Porter the limestone is about 50 feet 



26 



