22 Frederick Chapman: 



granite appear in this area, having a general north-westerly trend, 

 and there are indications of the superimposed Tertiary beds having 

 been displaced in that direction. ThiiS, indeed, may account lor 

 the occurrence of the Soak in this desert country, far away from 

 anv other visible water-hole, except some salt lakes, as Lake Talla- 

 cootra, to the south, and which are evidently, due to a similar cause. 

 It is just possible that sub-artesian water is tapped here, and re- 

 mains held up by the heavier or impervious shell-marls of the Plei- 

 stocene deposit. 



Ihe collection made by Mr. Chandler comprises both Janjukian, 

 or Miocene fossils (mainly as casts), and some Older Pleistocene 

 material, cemented together or in loose specimens. 



The small but interesting collection made by Dr. Griffith Taylor 

 was from Janjukian beds. The specimens include a hard lime- 

 stone with Chlamys cf. murrayanus, Tate sp., and two examples of 

 a Janjukian coral, Orhicella (olim Ileliastraea) tasmaniensis,. Dun- 

 can sp., which li!vd rarely before been found outside of Tasmania. 

 This Orhicella , Mr. Cudmore informs me is abundantly scattered 

 over various parts of the Plains. 



Ihe collection made by Mr. Cudmore comprises more than a 

 hundred specimens. They are chiefly preserved in a hard ochreous 

 and white limestone, generally as casts and moulds, although some 

 still retain the shell structures, as Chlamys^ murrayanus. Mr. Cud. 

 more's specimens came principally from the Ooldea Well (not used), 

 300 yards west and 200 yards south of Ooldea railway station, 

 though a few of similar kinds were obtained from the half-mile 

 cutting at Watson, next to Ooldea, on the road to West Australia. 

 The limestone country is well shown by photographs here reproduced, 

 taken by Mr. Cudmore. 



On glancing at the geological map of this district, one sees that 

 Ooldea is situated on the later Tertiary bed, but close to the boun- 

 dary of outcrop of the Miocene series. From the disposition of the 

 two Tertiary beds, as mapped, it would appear probable that the 

 Pleistocene deposit represents a fairly shallow marine bed laid 

 down upon, and flanking a Miocene limestone, which extended 

 south-eastward as a promontory, as far as long. 133°30' at the 

 present time, as now seen exposed in the elevated plains. From 

 the fact that the Ooldea Soak is fresh, it is highly probable that 

 the water is deep-seated, and has its origin in or below the mass of 

 Miocene limestone, which must here be faulted, as seems to be 

 indicated by the sporadic but linear arrangement of inliers of 

 deep-seated rocks, and is not an ordinary soak in an impervious 



