THo:\rsox. — Geolorpi of MidiUc (.'larcuce and I' re V(i//('i/><. 347 



fauna. Obviously, then, in the iiorth-eastern ])art of t!i<» South Isliind 

 and the south-eastern ])art of tlie Nortli Island a marine transgression 

 commenced in the Upjier Oamaruian and continued into the Waitotaran. 

 It apjiears to have covered areas of pre-Notocene rocks not submerged in 

 the earlier Notocene transgressions, since no bould'M-s of these rocks are 

 found in its Ixisal conglomerates so far as examined, and this could hardlv 

 be tlie ease if a cover of Notocene from Clarentian to Oamaruian had been 

 stri])ped off the pre-Notocene. The Awatere series is absent from the 

 uj^pev ))art of the Awatere Valley, and ):)robably never covered this area, 

 since in the lower valley the beds are involved along the Awatere fault 

 and it would be reasonable to ex})ect to find them similarly involved in the 

 upper valley if they were ever present there. It a[)pears, therefore, as if 

 differential earth-movements were at least a partial cause of the Awatere 

 transgression. We have, then, an emergence of the Clarence and Kekerangu 

 areas during the formation of the great Marlboroutjh conglomerate, and a 

 transoression of the sea over the Awatere area, and both these events took 

 place in the Upper Oamaruian. It appears that they followed one another 

 in the order named, and that the .\watere transgression affected the 

 Clarence and Kekerangu areas. 



In Deadman's t^reek the u})per outcrop of conglomerate is followed by 

 a well-bedded marine series of sandstones and fine-grained conglomerates 

 passing up into mudstones. The geology of the area between the upj^er 

 part of Deadman's Creek and (larence Mouth is unknown, but from the 

 accounts given me by settlers it seems that there is a considerable extent 

 of blue mudstone, or '' |)apa," containing fossils at Parakawa. The marine 

 rocks followii]g the conglomerate can hardlv be other than the repre- 

 sentatives of the Awatere transgression, wliich may have a considerable 

 development in this district. From McKay's descriptions it is evident 

 that similar rocks are present following the conglomerate in the Bluff 

 River. He states that these beds are so like the '' grey marls " in a])|)ear- 

 ance that it is hard to distinguish them. . As at Deadman's Creek, they 

 are separated from the coarser layers of the conglomerate by beds of sand- 

 stone and fine conglomerate. 01>viously the evidence of fossils is necessary 

 to confirm this correlation of the marine beds above the conglomerate with 

 the .4watere beds. 



The existence of tliese overlying marine beds proves that the Clarence 

 and Kekerangu areas, in which a tiuviatile deposit was forming, g7'aduallv 

 became submerged. The j)resence of a fairly thick series of sandv mud- 

 stones at the Bluff River suggests that the submergence was considerable — ■ 

 at least over 600 ft. — since the beds are a])parently foreset, and that the 

 continental shelf of which they formed a part had an abundant supplv 

 of fine waste. Cotton estimated the differential movement necessajy for 

 the formation of the conglomerate as perhaps as much as 12,000 ft. (the 

 maxinuim thickness of the Notocene up to the to]) of the " grey marls "), 

 but, as tlie average thickness of the Clarentian is only about 3.000 ft., 

 a differential elevation of 6.000 ft. would be sufficient to account for the 

 features of the conglomerate. If the elevated area were also tilted, as 

 is conceivable, an elevation of half this amount might sufl[ice. In the 

 formation of 400-600 ft. of conglomerate the relief of this elevated area, 

 especiallv near the fault-scarp, would be considerablv reduced, and by a 

 subsequent drowning of, say, 1,000 ft. the relief would be further reduced. 

 The nature of the beds of the marine series following the conglomerate 

 is not inconsistent with Cotton's explanation of its origin. Although it is 

 not necessary to conclude that the conglomerate was everywhere submerged 



