552 Clarke — Geology of Western Australia. 



Hunt's country ; and, according to Gregory, at the Mounts Barren 

 on the south coast, and on the flanks of the Darling Eange, as well 

 as at the heads of the Lyons and Grascoyne Kivers on the north- 

 west. 



Mr. Lefroy gives the localities in which he found the relics of old 

 sedimentary formations, as gneiss or mica-schist in 29° 50^ S., 

 122° W E., and in 29° 53' S., 121° 21' E. In 31° 8' S. and 119° 

 49' E., a talcose slate occurred ; and quartziferous schists are men- 

 tioned in 31° 8' S., 119° 49' E. as well as metamorphic slates in 

 30° 5' S. and 121° E. ; the slates being 'polished in 29° 53' S., and 

 121° 21' E. So that, incorporating Mr. Lefroy's experience with 

 that recorded in Mr. Hunt's map, we may assert, that over an area 

 of very nearly 9000 square miles those gentlemen have established 

 the fact, that fragmentary ancient or metamorphic schists occur at 

 repeated intervals, whilst Mr. Lefroy states that a kind of dip or 

 slope of the surface of the granite exists to the southward, and Mr. 

 Hunt gives reason to believe, that the granite rises into loftier 

 elevation towards the north, and, so far as I can decipher from the 

 collection forwarded to me, has an extreme termination somewhere 

 about 122° E.. near the limits of his exploration. 



The agreement between Mr. Lefroy and Mr. Hunt is considerable 

 as to the occurrence of the overlying rocks in fragmentary beds. 

 Thus, No. 4 in Mr. Hunt's collection is a gneissose rock, and Nos. 

 1, 2, 3, and 13 are clay slates, all of which have an air of great 

 antiquity, and correspond in texture and composition with rocks of 

 the same name in the Lower Silurian series. 



Neither Mr. Hunt nor Mr. Lefroy indicate any formation inter- 

 mediate between these schists and what are probably Tertiary 

 deposits. But it must be remembered that near Mount Barren on 

 the South, and near Champion Bay on the north-west side of the 

 imagined granitic boss, a Carboniferous formation exists, succeeded 

 in the latter neighbourhood by Secondary formations ranging as 

 high as Cretaceous. Regarded in this light, we have the relics in 

 consecutive order of the members of the geological scale without 

 any anomaly ; and quite in agreement, when looked at in a broad 

 view, with the features of other, though more limited regions. 



In regular order we ought to have the comiug in of the Tertiary 

 formations. Such appear to be indicated by Nos. 29, 35, and 37 in 

 Mr. Hunt's collection, as well as in some others, and by the mention 

 on his map of drift gypsum in 119° 30' E., a . mineral of some 

 importance further to the east in the low regions of the northern, 

 north-western, and western part of South Australia. 



Besides the above indications, we have in Mr. Hunt's collection a 

 very numerous series of aluminous deposits of various colours, which, 

 at my request to him, have been submitted to analysis by Mr. 

 Theodor Staiger, of Hobart Town. His chemical determination 

 agrees remarkably with the conclusions I have come to, on different 

 grounds. 



Similar deposits, sometimes resembling chalk, are well known in 

 the settled parts of Western Australia and in New South Wales, and 



