344 Transactions. 



" The encrustation contains a small quantity of free sulpliur. The water 

 extract showed the presence of ferrous sulphate and small quantities of 

 calcium and magnesium salts." The efflorescence or encrustation is presum- 

 ably due to the oxidation of sulphide of iron, present mostly in a state of 

 fine division in the rocks, but partly in well-defined small nodular con- 

 cretions. The name of " saurian beds " is given because of the presence 

 of large concretions containing saurian bones in the upper part of the 

 sulphur sands and the lower part of the sulphur mudstones. This is the 

 horizon from which most of the Piripauan saurians have been obtained 

 both in this district and at Arauri Bluff ; but it should be noted that speci- 

 mens have also been obtained both in the underlying coal-measures and in 

 the overlying Waipara greensands. The latter rocks have usually been 

 termed the concretionary greensands ; but this name is unsatisfactory- — first, 

 because the concretionary beds compose only the lower part of the green- 

 sands, and, second, because there is a higher greensand horizon with true 

 concretions to which the name might equally refer. 



The Ostrea bed in the Waipara River is followed by clean white sands, 

 containing a few carbonaceous shaly partings near their base. After about 

 100 ft. they become much more argillaceous, and pass finally into streaky 

 rocks, forming grey cliffs, and consist, when freshly broken, of a dark mud- 

 stone matrix containing lighter-coloured streaks of glauconite and quartz 

 sand in a calcareous base. At about -300 ft. above the Ostrea bed there 

 is a thin band, about 6 ft. thick, consisting mainly of quartz sand and 

 glauconite. This is succeeded by purple micaceous nmdstones with a 

 shaly parting, which are perhaps 200 ft. thick. The sulphur efflorescence 

 commences after the first 50 ft. of sands, and continues in greater or less 

 intensity throughout. Well-defined, nearly circular concretions, mostly from 

 4 ft. to 9 ft. in diameter, commence about 100 ft. above the Ostrea bed, and 

 continue along certain planes for a'bout 200 ft. (Plate XVII, fig. 2). Further 

 similar concretions reappear in the middle and upper part of the purple 

 mudstones. The concretions are formed of hard calcareous sandstone, and 

 consist of grains of quartz with subordinate feldspar, glauconite, magnetite, 

 and muscovite, set in a calcareous cement which is occasionally poecihtic, 

 the individual calcite crystals being sometimes as much as an inch in 

 diameter. 



Fossils are not common in these concretions, but, owing to the keen 

 search that has been made for saurian bones, a large number has been 

 collected. McKay (1892) noted that out of a total of some 250 " boulders " 

 examined only six or eight proved shell-bearing, and three were rich in 

 shells. Usually in the shell-bearing concretion there is a mixture of 

 nionocotyledonous and dicotyledonous plant-remains.- The pelecypods col- 

 lected by McKay from this locaUty were determined by Woods (1917) as 

 follows : Malletia (Neilo) cymbula Woods, Trigonia waiparensis Woods, and 

 Thracia sp. In addition imperfect specimens of Belemnites were included, 

 and gasteropods, which were sent to- Professor Wilckens, of Jena, before 

 the war, and have not yet been described. The Reptilia collected from the 

 " saurian beds " in this vicinity by Hood, Holmes, von Haast, and McKay, 

 as determined by Owen, von Haast, Hector, and Lydekker, were : Leiodon 

 haumuriensis Hector, Cimoliosaurus australis (Owen), C. hoodi (Owen), 

 C. Jwlmesi (Hector), and C. haasti (Hector). Hood collected other speci- 

 mens, which were lost in the s.s. " Matoaka," including bones which he 

 judged to belong to Teleosaurus, but Hector (1874) considered it probable 

 that the specimens should be referred to Leiodon. 



