336 Ernest W. Skeats : 



stages can be traced between a compact diabase through stages 

 more and more silicious to a bright red jasperoid. The jasperoid 

 here is of quite limited occurrence, and passes outwards in all 

 directions into the dark, dense diabase. Silica-bearing solutions 

 appear to have traversed the rock along some joint or fracture 

 plane, and have altered the rock for a foot or two from 

 a central point. The jasperoid is itself traversed by later 

 formed white quartz veins. 



Under the microscope (No. 549) (PL XV., Fig. 3) the original 

 structure and minerals of the diabase have been completely lost. 

 The rock now consists of a chalcedonic replacement, stained red by 

 hematite, probably derived from iron containing minerals in 

 the original diabase. The deposition of the iron-oxidc'S has 

 been irregular, darker and opaque areas passing across the 

 section in bands. The chalcedony has crystallised from centres 

 in radiating groups of crystals. Their boundaries are defined 

 in the rock section by colourless lines of secondaiy silica. In 

 polarised light these radiating aggregates show irregular black 

 crosses. 



In allotments 3q and 3m, Knowsley East, a thin strip of 

 metamorphio is shown on the map, while the diabase is not 

 represented. I have shown above that foliated diabase actually 

 occurs, and some at least of the outcrop of " Metamorphic '' is 

 in reality jasperised diabase. 



In the Heathcote district it is safe to regard the jasperoid, 

 wherever found, as being one of tlie forms of silicified diabase. 



(\iIcareo-siliceous EocJcs. — A strip of very altered rocks occurs 

 in South Heathoote, extending to the N. VV^. from just north of the 

 South Heathoote Hotel, crossing the main road, and terminating 

 against the micro-granite near the railway cutting at the back 

 of the Ben Nevis Hotel. Its character varies from place to 

 place. At one spot it is almost a carbonate rock, in another 

 almost a chert, and greenish patches, sporadically developed, 

 resemble selwynite in colour, being probably due to the separation 

 of oxide of chromium. It was originally a diabase rock. A 

 section taken from an outcrop 200 yards N.W. of the S. Heath- 

 oote Hotel will serve to illustrate some of the characters of the 

 rock. Under the microscope (No. 592) (PI. XV., Fig. 4) one can 

 trace two stau;es in the alteration of the original rock. It was first 



