27 



-porous and water bearing, but of unknown thickness, nor is it 

 known what is below it, as at a depth of, I believe, about 200 

 :feet reached by boring near the hotel in search for kerosine or 

 coal, the base rock was not reached. The river crosses the 

 flat obliquely east of the township, no where showing rocks in 

 the bed, but instead has mostly boggy banks on account of the 

 many springs, usually weak and some saline in summer. An old 

 bed, now broad and shallow, winds through and west of the 

 township, joining the river where it approaches the western hills. 

 Its watershed on this side is very close, only from half a mile to 

 two miles distant, and skirting it, an interrupted band of the 

 well-known " Ironstone " occurs, probably marking the edge of 

 the former lake, but is wholly absent on the eastern side. In 

 structure it varies from that of a real sandstone finely and evenly 

 grained to a coarse conglomerate of pebbles three to six inches 

 in diameter. Sometimes cavities, as if shells had been removed, 

 are found in it, but no fossils were ever seen here, except a frag- 

 ment of wood converted into brown haematite, found S.W. of 

 Tanunda. 



Where undisturbed and developed to a considerable extent the 

 uneven surface is homogeneous, but with occasional round holes 

 penetrating deeply and allowing the water to flow off*. Its 

 thickness is nowhere exceeding two feet. 



A very interesting rock is a very hard grey sandstone grit, 

 which here and there is found fringing low ridges. It conssts of 

 pure grains of semitransparent quartz cemented by silica of the 

 same character and inclosing a few larger pebbles but rarely. 

 Sparingly dispersed occur tortuous holes, as if formed by worms. 

 This rock is from 18 inches to three feet thick, rests on red clay, 

 and is sometimes overlain by the ironstone. A similar but more 

 jaspery rock occurs on the hillsides near Sheaoak Log, showing 

 numerous root-like enclosures. 



The older rocks in the eastern as well as the western hill 

 ranges consist of micaceous and hornblendic schists, gneiss, 

 quartzites, and near Greenock granite. The last is intrusive at 

 and near the anticline, which is at a high angle. It outcrops only 

 near the base of depressions, but never on the heights. The 

 principal place observed is in the north-east corner of section 

 1817, near Greenock, and indications in section 208. 



The strike of the old pre-silurian rocks varies a few degrees 

 beyond the magnetic and true north and south, while the dip is 

 usually at very high angles. At Angaston, in a small quarry 

 near Mr. Salter's residence, the hornblendic strata are undulat- 

 ing, and the dip varying between 48° and 65° westerly (strike 

 N., 7° W.). Similar strata near Greenock, in the cutting of the 

 road, gave a similar strike, but a dip of 62° to 68° easterly, while 



