Rocks near HeafJicote. 319 



strike of the beds gives an almost continuous exposure of these 

 rocks, wliich pass into what is mapped as normal Ordovician. 

 Strike and dip were obseiTed at several points along the section, 

 and were found to remain practically constant. The rocks 

 plainly hero form a continuous series without stratigraphical 

 break, and the inference is that the schistose fragmental diabase 

 rooks form the lowest repi^sentatives of the Ordovician series 

 at this point (Plate XVII., Fig. 2). Following them northwards 

 is a puckered shaly rock with surface outcrops of an alteration 

 to ironstone, and to ferruginous cherts. At the beacon marking 

 the summit of Red Hill the dump from an old mining shaft 

 shows silky shales almost completely altered to chert. On the 

 northern slopes of the hill not far north of the Beacon these give 

 place to very decomposed, greasy-feeling shales, and N. and N.W. 

 of these black cherts ai-e again seen, and form the most northerly 

 of these beds on Red Hill. "West of Red Hill the ground shjpes 

 to a gully, and the veiy limited exposures do not permit a close 

 examination of the relations of this series to the normal Ordo- 

 vician*. Dips and strikes, however, in the two series, whenever 

 they could be obsen-ed, were fairly concordant. At the S. end 

 of the hill strikes E. and W. were noticed ; further north both 

 series showed W.N.W. strikes. Xo break in the succession was 

 seen, and no conglomerates were noticed. The field evidence 

 points strongly to the ironstones and grey and black cherts 

 being simply highly altered representatives of the schistose frag- 

 mental diabasic bedded rocks at the S. end of Red Hill, and all 

 these types should be included not with the pre-Ordovician, as 

 Prof. Gregory maintains, but as the oldest representatives in 

 this locality of the Ordovician series. Beyond the gully, run- 

 ning S.W. at the W. end of Red Hill, cherty Ordovician extends 

 along the contact up to the small patch of Pliocene shown on the 

 map. Beyond this the contact for about a mile has not been 

 examined by me. A hill composed of black finely-bedded and 

 folded cherts occurs about 250 yards W. of the Derrinal road, 

 and about 300 yards N.W. of junction of the Derrinal and 

 Murray roads. The hill is about 150 yards S. of crossing 51 on 

 the railway. The dip is 90 deg., and strike W.S.W. It is shown 

 on the early map as diabase, and it is indeed in contact with 

 diabase. It appears at first sight to be a normal shale silicified 



