420 Transactions.^Geology. 



FORAMINIFEROUS ClAYS. 



These clays form the basement rock of this place. They 

 are exposed at the north end of Waikouaiti Beach, where 

 they occur as a flat gently shelving plane lying below high- 

 water mark. A few chains around the rocky beach they rise- 

 in two places into the sea-cliif, a height of some 30 ft., forming 

 small exposures in the face of the sandstone talus by which 

 they are surmounted and surrounded. 



In most places the clays are somewhat sandy, and where 

 exposed to the weather are friable and crumbling and of a 

 pale-blue colour. At all the points where I examined them 

 they were found to contain a large assemblage of Foramini- 

 fcra, among which many genera were represented, embracing 

 forms possessing elaborate and beautiful shell-structures. 

 Besides Foraminifcra, I found some fragments of minute, 

 obscure bivalves, but the only genus I was able to identify 

 was a small Pecten. 



At the first cliff-exposure after leaving the end of the 

 sandy beach the clays contain irregular bands of dark-green 

 glauconitic sandstone varying from 1 in. to 4 in. or 5 in. thick, 

 except at the top of the outcrop, where there is a deposit 

 of greensand the actual extent of which is obscured by the 

 talus. The strike of the glauconitic veins exposed at the top- 

 of high-water mark is east-and-west, and the dip south at an 

 angle of 62°. Small nests, streaks, and spangles of iron- 

 pyrites, some of which look like replacements of organic 

 remains, are not infrequent in the clays and glauconitic sand- 

 stone. 



The clays are so obscured by the talus that their relation- 

 ship to the overlying sandstones cannot be ascertained at this 

 place. Mr. McKay, in his report on eastern Otago,* men- 

 tioned the occurrence of calcareous sandstones at Cornish 

 Head, but seemed to be unaware of the presence of the 

 blue clays. In his map, however, he shows a strip of what 

 he calls " marly clays " running from Waikouaiti Township 

 northward through the saddle leading to Pleasant River. He 

 does not appear to be clear as to the position of these clays, 

 as, speaking of them (page 6), he says, " These are the pro- 

 bable equivalents of the Maheno marls that on the left bank 

 of the Kakanui are seen resting on the Waireka tufas, and at 

 the same place replace or pass under the Ototara limestone." 

 In White Bluff, he continues, " they are overlain by a volcanic 

 breccia." Again, on page 237 of the same report, Mr. 

 McKay says, " These beds as they underlie the calcareous 

 sandstones " [Ototara stone] , " already described, are sup- 

 posed to form part of the sequence affected by the fault along 



♦ Reps. Geol. Expl., 1886-87, pp. 6-8. 



