of Mr. Curnow's garden (Sec. 833, Onkaparinga), as well as 

 on the road adjoining, that goes down to Pinkerton Gully. 

 The limestone is of a buff colour on the exterior, but is blue 

 within. At about 100 ft. lower in the series another outcrop 

 of blue limestone occurs, 45 ft. in thickness (dip south-east at 

 40° to 48°), and can be well seen in the cutting on the old 

 "Corkscrew" Road. On the new "Corkscrew" Road the same 

 beds are strongly developed at what is known as the 'blue- 

 bend," where they have been excavated in the construction of 

 the road. The scarp shows the limestone to be split up by 

 impure, earthy, and schistose bands, with layers of cherty 

 material (dip south-east at 20°). This exposure is at a con- 

 siderably lower level than the two outcrops mentioned as 

 occurring: at Montacute Church and on the edge of Pinkerton 

 Gully. It is possible that this low-level outcrop may be the 

 result of the great landslip that occurred in prehistoric times 

 and caused the precipitous cliff on the eastern side of the ridge. 

 It is the greatest landslip that I have hitherto seen. At the 

 base of the remarkable scarp, left by the slide, an extraordinary 

 anedley of piled-up rocks occurs, through which the older 

 "Corkscrew" Road was cut, and its effects can be traced to 

 the level of the valley below. A fault-plane may have existed 

 and created a line of weakness from which the imperfectly 

 supported rocks on the side of the steep valley slipped away. 



The "CorA'screir," Hunter Gulh^, Montacute Mine, etc. — 

 between the Montacute ridge and the old Montacute Mine there 

 are several parallel outcrops of the Upper Torrens-limestone. 

 It is not very clear whether these several calcareous horizons 

 are independent beds, and follow in consecutive order, or 

 whether they are repetitions of the same bed caused by strike- 

 faulting as occurs in other parts of the field. The limestone is 

 of very irregular development, varying from a calcareous shale 

 to lenticles of hard crystalline limestone. In this way there 

 is often an apparent want of continuity in the limestone, and 

 calcareous horizons may develop within the range of a consider- 

 able vertical thickness, which occasions some difficulty in 

 mapping. There are three such limestones in the locality now 

 under description, and it will be convenient to refer to them 

 respectively in ascending order as limestones a, h, and c. 



Outcrop (a ). From the hill-top, near Montacute Church, 

 the- blue limestone can be traced along the southern side of the 

 valley, going down the "Corkscrew," and faces into Mr. 

 Trebilcock's garden (Sec. 834). It crosses the spur near the 

 bottom of the valley (Hunter Gully), and passes up and over 

 the ridge on the opposite side (Sec. 5525), making strong out- 

 •€rops in places. In the next gully (Cock's), going east, it is 



