318 Ernest W. Skeats : 



the Felspar Porph}T*ite. The rock in the frullv S. of Photo. 

 Knob is a rather coarser type in which the fragmental character ' 

 can be made out (Sect. 582), while the Knob itself represents /^/L<f 

 coarse consolidated agglomerafe, probably occupying" the neck of r^ 

 a vent. This interpretation would remove the evidence of uncon- 

 formable overlap of the Ordovicians N. of the felspar porphy- 

 rite claimed by Professor Gregory at this point. It is to be 

 noted that the Felspar Porphyrite occupies a considerably smaller 

 outcrop than is showm on the earlier map. West of the diabase 

 and felspar porphyrite partially chertified Ordovician was seen 

 at several points, but no good exposures were visible. The mar- 

 ginal Ordovician continueis cherty to the gully south of the 

 small Diorite Knob shown on the map. Here again I have 

 altered the geological boimdaries. The black cherts and very 

 silicified rocks extend round the E. and S.E. sides of the diorite, 

 and also in a somewhat less silicified form for about ^0 yards on 

 the w^est and south-w^est sides. A trench about 40 yards west of 

 the diorite shows Ordovician shales, in places indurated and 

 containing sporadic nodular lumps of cherty carbonates. The 

 rocks here are vertical, and strike X. 40 deg. W. The same 

 strike is noticed in a creek about 150 yards W. of diorite, and 

 in much silicified shales 20 yards X.W. of the diorite, and also 

 in the black cherts seen a few yards further north. Rock ex- 

 posures are so limited that the relations between the bLack cherts 

 and slightly cherty Ordovicians are not seen, but the e^-idence 

 of dip and strike discloses no discontinuity. The black cherts 

 extend much further to the N.W. than was shown on the earlier 

 map, and have been traced beyond the next gully to the N., 

 and then N.E. to wdthin a few hundred yards S. of Crossing No. 

 45, where they come in contact with the granitic series. The 

 marginal Ordovician continues to show evidence of silicification 

 northerly as far as the gully at the S. end of Red Hill. 



Between the diabase of Red Hill and the normal Ordovician 

 occurs a narrow strip of rocks marked as metamorphic, and 

 described as schistose beds by Prof. Gregory, which extend fur- 

 ther both to S. and N. than i« shown on the earlier map, and 

 whose relations to both series are not very clear. At the S. end 

 of Red Hill they are fragmental beds apparently made of diabasio 

 material. A small gully running S.W. from here across the 



