Th<> Hmthcotian. 16^ 



the typical cherts of the inetamorphic series occurs along t he- 

 eastern edge of allotment 3Q in Knowsley East. The cherts 

 occur between the silurian rocks on one side and unaltered 

 ordovician on the west. There are some diabases a little south 

 of this allotment, but none occur in it. If we explain the 

 metamorphisni there as due to a continuation of the diabases at 

 a sliglit depth below the surface, then it is difficult to understand 

 why there is no sign of alteration in the Dinesus ida beds, which 

 must be approximately the same distance from any such assumed 

 igneous mass. 



Further evidence of a negative, but still of an important 

 chai'acter is the fact that, although these diabases and igneous 

 rocks occur along a line of nearly thirty miles in length, not one 

 case is known of an apophysis or of a dyke striking from this 

 series into the silurian or ordovician beds. Had this complex 

 series of intrusive igneous rocks been injected- in post silurian 

 times, it is highly improbable that they should have kept along 

 the actual line between the two lower palaeozoic system;?, and 

 should not, in a single case, have sent off* an intrusion into the 

 lower palaeozoic beds. 



Q.—Geolflqical Sequence at Heathcoie. 



The evidence therefore seems to nje conclusive that the series 



is as follows : — 



Silurian - - Sandstone and Quartzites. 



Unconformity. 



. . i Sandstones and slates. 



Ordovician \ ^. • i i i 



V Dmesus ida beds. 



Granodiorites and granupliyric porphyrites. 



Diabase series partly eruptive and partly in- 



Heathcotian , 



trusive 



Cherts and schists. 

 Accoi-ding to this view, Mr. Dunn was right in regarding the 

 rocks in the Heathcote series as pre-ordovician (or as he has put 

 it, pre-silurian), and the diabases as in part effusive. ^\\\ 

 Howitt was right in his rock determinations, and in the view 

 that the diabase and acid rocks are mainly intrusive ; but Ijoth 



