Uttley. — Remarks on Bulletin No. 20. 179 



very abundant, but unfortunately mainly in the form of casts. From this 

 horizon at Black Point, McKay and Park made extensive collections, and 

 forty-three species were determined by the late Mr. Henry Suter, and 

 referred by Park to his Bortonian. In another paper in this volume the 

 writer has given a list of fossils, also determined by Suter, which were 

 collected from an horizon about 30 ft. above the coal-grits, and almost 

 certainly represent the Bortonian horizon. At Ngapara a similar fossil- 

 iferous bed is found lying a short distance above the Coal-rocks. In the 

 bed of the Kakanui River, near Gemmel's crossing, this fossiliferous 

 horizon occurs beneath glauconitic greensands, which dip beneath the 

 Waiarekan tuffs of the Oamaru district. The introduction of a Bortonian 

 horizon should be favourably received by geologists. Park has stated 

 that " for a classification to be a trustworthy standard of reference it is 

 an essential requirement that the subdivision shall be made in a district 

 where the component subdivisions are in such intimate association that 

 their relationship to one another can never be in doubt." All will accord 

 hearty approval to this dictum; but we may also add that, if an attempt 

 is being made to work out a distinctive fauna for each of these component 

 subdivisions, it is also an essential requirement that the fossils shall be 

 definitely ascertained to have come from a definite horizon. This does 

 not mean that fossil lists should be discarded merely because their horizon 

 is doubtful, but it does mean that these doubtful fossils should be rejected, 

 temporarily probably, when lists typical of the various stages of a system 

 arp being compiled. The species listed by Park as Bortonian and Upper 

 Waiarekan call for some comment in the light of the principles just, 

 enunciated. The fossils from the beds at Black Point number forty-three 

 species (p. 34), and were gathered from Park's typical Bortonian locality, 

 and the horizon is undoubted. On page 35 a list of thirteen species of 

 Mollusca is given from brown sandstones which lie " about 80 ft. above 

 the lignitic quartzose beds of the Ngaparan stage, and may represent a 

 somewhat higher horizon than the Bortonian." On the same page is given 

 a list of fossils gathered from fossiliferous blocks, but " these masses could 

 not be traced to their source." As the horizon of the first collection is 

 doubtful, and as the second was derived from rocks that were not in situ, 

 these fossils cannot be included in the typical Bortonian. The list of sixty- 

 four species must therefore be reduced to forty-three species. 



(2.) Upper Waiarekan. 



The writer (1918a, p. 107) attempted to define the horizons of the 

 volcanic rocks in the Oamaru district, and concluded that there was a period 

 of volcanic activity prior to the deposition of the Ototaran limestone, repre- 

 sented by the Waiareka tuffs (Upper Waiarekan of Park), and that there 

 was a later period — perhaps two later periods — of activity represented by 

 the volcanic rocks that occur interbedded with the Ototaran limestone 

 near Oamaru. Park recognizes three periods, the second and third being 

 Ototaran, while the first period is Upper Waiarekan. These volcanic 

 rocks form fragmental tufaceous beds for the most part, and were probably 

 all accumulations from submarine eruptions ; they are often fossiliferous, 

 Fossils gathered from tufaceous rocks may therefore be either Ototaran or 

 Waiarekan, and before the fossils are assigned to either of these^ horizons 

 the position of the bed must be indisputable. The fossils listed as Upper 

 . Waiarekan by Park have in nearly all cases been gathered from beds inter- 

 bedded with limestone, and the writer believes that they belong to the 

 limestone period — that is, they are of Ototaran age. Park himself indicates 



