PaOCEEDIXOS OF SECTION E. 057 



from 100 to 200 j^ards at the base. There is no evidence of the 

 sand having been blown along the surface, or transported from 

 ■•). distance by water flowing over the surface of the ground, which 

 is, as a rule, quite clear of sand between the hills. I have reason 

 to believe that in many cases, particularly in those of the isolated 

 ridges and mounds traversing the stony desert at long distances 

 apart, the sand has been derived from an underground source 

 through the pressure of subterranean water. There was, in all 

 probability, an outlet at one time connecting the old cretaceous 

 sea, which occupied the centre of Australia, with the ocean. If 

 we suppose a sudden or gradual closing up of this outlet to have 

 taken place through the subsidence of the land, or any other 

 cause, the water, not having any vent to escape by, would accumu- 

 late in the porous strata until, under sufficient pressure, it would 

 force its way to the surface along cracks or through holes caused 

 by such pressure, and bring with it the sand, in a similar manner 

 to the present mud and sand springs. The eruption of sand in 

 large quantities would cause a subsidence of the surrounding area, 

 whereof there is evidence in the valleys of the Cooper and Diaraan- 

 tina, and thus have created the great lakes into which these 

 rivers now flow. About 35 miles south-east of Clifton Hill Sta- 

 tion, on the Diamantina, there are two parallel red sand ridges 

 traversing a stony plain in a north-north-westerly direction ; the 

 plain is covered with a pavement-like coating of flinty quartzite 

 stones. On the east side blocks and boulders of the same rock are 

 scattered about, amongst which are numerous low circular mounds 

 cf white clayey sand, the centimes of which are formed of blocks 

 of stones piled up, which are encircled by other smaller blocks, 

 and these by scattered stones, the whole bearing the appearance 

 of having been erupted by springs from below. At numerous 

 other places similar appearances present themselves, mounds of 

 sand, gravel, and clay, and scattered stones occurring on the sur- 

 face of many of the plains and flat areas, the presence of which 

 it is difficult to account for in any other way, as there are no rocks 

 at a higher level in the neighbourhood from which sand or gravel 

 could have been washed." 



At a later date, when discussing with Mr. Brown the booming 

 sounds occasionally heard in the far north, he was inclined to the 

 opinion that the eruptions of sand referred to in his report were 

 probably accompanied by detonations. 



On the 3rd November, 1877, over the signature " Tom Porter," 

 the following appeared in the South Australian Register: — 



" Possibly some scientist will kindly explain what caused some, 

 to me, strange noises I heard just as it was getting dark on 7th 

 or 8th May, on a run in the north-west. 



" I was riding facing the west when a flash of very red light 

 filled the air, and made me pull up and look in every direction, 

 for it was totally different to the flash of a shooting star, and the 



