The Heathcot'ian. 161 



doubt, after the application of the luicroscope, as to whether a 

 rock belonged to the schistose or to the ordovician series. 



In Craven's paddock, in Knowsley parish, allotment 32, the 

 two rocks can be well seen in contact close along the eastern 

 fence. Here, as elsewhere, the junction between the hard 

 cherts of the metamorphic series and the normal slates and sand- 

 stones of the ordovician series can be clearly recognised. 



A serious difficulty in the view that the diabase rocks were 

 intrusive into the ordovician rocks is the spoi-adic character of 

 contact alteration along the line of junction. Thus in Mr. 0. A. 

 L. Whitelaw's sketch map of Heathcote, the diabases are repre- 

 sented in contact with the ordovician rocks from the northern 

 boundaiy of the parish across Mount Ida Creek and Mclvor 

 Creek to the west of the northern end of tlie township. Along 

 this line of two and a half miles no metamorphic i-ocks are 

 represented as occurring between the ordovician and diabase 

 series. In the Heathcote township there are two blocks of 

 metamorphic rocks. One is shown on the map to the north and 

 east of the water reserve ; but these metamorphic rocks, instead 

 of occurring between the diabase rocks and the ordovician, are 

 on the wrong side of the igneous series. A sraall narrow band 

 of metamorphic rocks occurs at Red Hill ; it is a quarter of a 

 mile in length, about ninety yards in width at tlie thickest point;, 

 it thins out to north and south, leaving unaltered ordovician rocks 

 resting directly upon the diabases. Then follows another 

 mile and a half without any metamorphic rocks along the 

 contact; then, close by a small patcli of diorite on the eastern 

 side of the road going to Arygle's reef, there is another patch of 

 metamorphic rock (PI. XXTV., Fig. 1). It forms a b;iy 

 running into the diabase series, which occurs round it 

 on the north and east; on the south is a small out- 

 crop of diorite, which appears to be sliarply marked off from 

 the ordovician rocks by a line running from north-west 

 to south-east. This line cuts with equal abruptness straight 

 across the metamorphic rocks, the diorite and the diabase, as if 

 they were all part of the same series. The last patcli of the 

 metamorphic rocks occurs in South Heathcote, in allotments 

 Nos. 15 and 16 (PI. XXIV., Fig. 'l). Here a bay, re- 

 presented on the map as unaltered ordovician, runs up 



