Rocks near Heathcote. 321 



igneous rocks exposed in the immediate vicinity. Thus an ex- 

 posure of the typical cherts of the metamoiphic series occurs 

 ahmg the eastern edge of allotment 3q in Knnwsley East. The 

 cherts occur between the Silurian rocks on one side, and unal- 

 tered Ordovician on the west. There are some diabases a little 

 south of this allotment, but none occur in it." I am unable to 

 reconcile the mapping and Professor Gregory's statements with 

 my own obsen-ations at this point. At the S. end of allotment 

 3q, near the Murray road, is a limited outcrop of a bedded rock 

 in hand specimen like a quartzite, and associated with it is a 

 dark, dense cherty rock. Microscopic examination shows that 

 the latter (Sect. 651) is a diabasic rock, probably fragmental, 

 which has been almost completely silicified. I am less positive 

 about the origin of the former (Sect. 588) ; it may be a quartzite, 

 but it presents apjjearances which suggest that it may represent 

 an extreme stage of replacement of a diabasic rock by silica. 

 Just W. of this outcrop foliated or platy diabase occurs, similar 

 to that on Red Hill, and, indeed, fragments occur fairly abun- 

 dantly on the surface goinir northwards along allotment 3q, 

 between tho road and the outcrop of the Dinesus beds, which 

 here, as elsewhere, are frequently chertified. 



This evidence is of importance, as from the assumed absence 

 of diabase in this locality, Professor Gregory infe-rred that the 

 Ordovician overlaps and rests unconformably on the metamorphic 

 oherty series. 



An isolated area of diabase is shown on the map, occupying 

 an allotment with the letters M of W, and indicated on the 

 Parish Map of Knowsley East as Tranter's Paddock. It is repre- 

 sented as surrounded by .normal Ordovician. It consists mainly 

 of a platy variety of diabase similar to that on Red Hill, and 

 probably representing an altered tuff. Near the margin it is 

 highly silicified, and in places is converted into a black dense 

 chert. Tlie rock mapped as Ordovician, with which it comes in 

 contact, is well bedded, generally considerably silicified, and 

 cavernous, owing to the removal of crystals by solution from the 

 rock. In general appearance under the microscope it strongly 

 resembles a submarine bedded tuff. 



An almost identical rock occux's just W. of S. Heathcote 

 railway station, in what is mapped as Diabase ; some of the 



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