273 
take their place. About 200 yards higher up the hill than 
where the limestone beds reach the district road there is an 
outcrop of tertiary beds which follow the сгез of the hill, 
nearly to the banks of the Onkaparinga, and are more or 
less covered with a travertine crust, which must not be con- 
founded with the travertine of the older formations. The 
corresponding hill, on the opposite side of the main road, is 
also composed of tertiary calcareous sandstones and traver- 
tine. 
From the trend of the limestone from Hackham, the line 
of strike should intersect the Onkaparinga near Noarlunga; 
but these beds are not met with in the river section until & 
point is reached one and a half miles above the township. 
There is, therefore, a lateral displacement of the beds to 
this extent by the great dip fault. 
The beds re-appear on the ridge road (which.runs along the 
north side of the Onkaparinga), at the junction of a steep 
district road that follows down a gully and crosses the river 
at the Ford, between Sections 48 and 56. Here the two most 
important faults (B and C) of the district intersect. The lime- 
Stone, which has been thrown a mile and a half east by the dip 
fault, is obliquely cut by another strike fault, running 
north-east and south-west. The paddock on the east side of 
the gully road is strongly ridged with limestone outcrops. 
The fault, with the limestone on its eastern side, crosses 
the gully road diagonally about half-way down to the river; 
and at a lower level the junction of the limestone, faulted 
against the purple slates, can be well studied, near the river 
level, on the western side of the road. The limestone shows 
discordant dips across its strike; but the general dip is to- 
wards the fault, viz., south-west at 40°; whilst the purple 
slates, which are greatly decomposed at and near the fault 
area, have a dip varying from 85° to 90? E. The limestone 
first dips to the fault, as stated, then easb, 20? south, at 30? 
passing into a synclinal fold, which gives a reading of 70° 
west: whilst the underlying earthy beds, which rise on the 
eastern side, have a dip of 80° west. The limestone at the 
bottom of the valley has a spread of eighty yards. 
The limestone crosses the Onkaparinga just east of the 
Ford, and skirts the scuthern rises of the river, on its left 
bank, going south. In the first gully below the Ford (Sec- 
tion 56) massive limestone outcrops make a prominent fea- 
ture, and an excellent transverse section of the fault area is 
seen. (See Plate xlii, fig. 4.) Тһе limestone is here 
exposed on both sides of the fault. On the west, or down- 
throw side, it forms a segment of an anticlinal curve, with 
a thiek covering of purple slates, which fold over into the 
R 
