64 THE GEOLOGIST. 



hills are partly granitic ; the granite is reddish, very readily decom- 

 posed, and worn by the rain and weather here and there into strange 

 grotesque figures. There are well- defined metallic lodes in this range. 

 East of these hills are three terraces leading down to the river. 

 The first is the broadest, extending about two-thirds the distance, 

 and falls twenty feet to the river. It is composed chiefly of sand ; 

 but rocks similar to those of the western rock crop out here and 

 there. The second terrace averages about two-ninths of the distance 

 betw^een the range and the river : it falls about thirty feet ; some- 

 times not more than ten or fifteen feet ; at places, however, more than 

 fifty feet. The third or lowest terrace is only one-ninth of the dis- 

 tance, and nearly level with the river : in fact, it is overflowed when 

 the water is up. The river itself flows slowly, having a fall of about 

 one foot a mile. It is at the fall or escarpment between the second 

 and the third terrace, on an exposed face of friable limestone, that 

 the peculiar substance referred to in this notice is found. The 

 whitish limestone (similar to the bryozoal limestone of the Mount 

 Gambler district) has its exposed edges excavated by innumerable 



burrows of wallabies, 

 kangaroo - rats, opos- 

 sums, etc., which live 

 and breed here in count- 

 less numbers, far in the 

 body of the rock, and 

 the upper part of the 

 openings of these bur- 

 rows are coated with a 

 softish-brown fetid ma- 

 terial, which appears to 

 be the concreted exhalations and effluvia coming from the heated in- 

 teriors of these long-inhabited and thickly tenanted burrows. The 

 concretion is thickest just within and at the mouth of a burrow, and 

 dies away upwards on the face of the rock, just as the stain of smoke 

 coming from a crevice is dark at the fissure, and becomes fainter and 

 fainter up the side of the wall. This material is several inches thick, 

 and, owing to the dryness of the climate, is not washed away by rain. 

 In England the specimens brought over are somewhat deliquescent. 

 It has not yet been examined chemically. 



This curious concomitant of cave-habitats in a warm and dry cli- 

 mate seems worth notice as connected with the subject of bone-caves. 

 The same country (South Australia) is likely to aflbrd valuable in- 

 formation rehxtive to the origin and early coridition of subterranean 

 caves and fissures ; for the limestone of the Mount Gambler district 

 is extensively excavated by subterranean drainage, on which the 

 water-supply of the towns and stations is, to a large extent, depen- 

 dent. 



The samples of brown material referred to in the above remarks were 

 obtained from a place on the Eiver Murray, near the Eeedy Creek 

 (Toongell) or the Thirty-nine Sections, called Poutarra, or Green 



