884 T ronxaction^. 



unconformities inserted by Hector is five. Some of these unconformities 

 that are inserted represent great lapses of time. Thus the plane between 

 the Waipara and Karamea systems of Park represents a period of erosion 

 extending throughout the Eocene and Oligocene periods. With Hutton 

 the Eocene is a period of erosion and elevation, but Hector's time-lapses 

 are of brief length, and therefore of relatively little importance. It is, 

 hovfever, obvious that an unconformity between Cretaceous and Miocene 

 rocks in Park's classification should be of such a marked nature as to be 

 a conspicuous feature in all the clear sections in the districts m which the 

 rocks are developed. 



Extremely different, too, are the periods to which the main portion of 

 the series, including at least the important coal-measures of the east coast, 

 have been referred. Hector places these in the Cretaceo-tertiary, Hutton 

 in the Oligocene, and Park in the Miocene. 



III. Classification proposed by the Authors. 



(a.) Discussion of Waipara Gorge and Weka Pass Sections. 



(See tig. 3 and Plate VIII.) 



The writers of this paper have long been conversant with these opinions, 

 and have seen grave reason to reject them in those portions of the Dominion 

 with which they are familiar. The doubts thus aroused caused them to 

 visit in company the more important of the sections upon the inspection 

 of which the classifications of the authors named were mainly based. 



Of these localities, it is admitted by every one that the gorge of the 

 Waipara River gives the most complete and satisfactory section, while 

 that of the Weka Pass is one on Avhich Hutton and Park have mainly relied 

 for the demonstration of the unconformities that they have described. The 

 third locality, the Amuri Bluff, is of importance because of the abundance 

 of fossils contained in the lower rock-series. 



The following quotations appear to us to represent the gist of previously 

 formed opinions on the rocks shown in these sections : — 



Hutton (N.Z.G.S. Rep., 1873-74, p. 44), at Waipara : " The W^eka Pass 

 stone is seen to rest on a water-worn surface of the Amuri limestone." Also, 

 p. 48 : " At Waipara the Pareora formation rests on the Trelissick group 

 without any appearance of unconformity." 



Haast (Geology Rep., 1871, p.-8):'"The beds [to top of Weka Pass 

 stone] follow in unbroken sequence — that is, they belong to the same series, 

 and mark a well-defined period in the past history of this portion of the 

 globe." Also, p. 16 : " After the deposition of the Weka Pass beds the 

 Avhole series seems to have risen to such an extent as to come under the 

 full destructive influence of tides and currents, if not even under subaerial 

 influence. However, the newer strata must in some instances have been 

 deposited very soon, as the uppermost beds of the Weka Pass have not only 

 been preserved entirely, so that no sign of denudation is visible, but the 

 Cucullaea beds overlie them in most instances so conformably that it is 

 impossible to detect the least difference in strike and dip." 



McKay (Geol. Rep., 1874-76, p. 39) : " At all points where the Weka 

 Pass beds are overlaid by any higher beds the marly grey or green beds 

 are the next in succession, and in many places they pass insensibly from 

 one to the other." Geol. Rep., 1890-1, p. 102 : " Although the change 

 from the Amuri limestone to the Weka Pass stone is somewhat sudden 

 and sufficiently clearlv marked, there is not in the cross-section exposed 



