Maclaren. — 0)1 Castle Bock, Coromandel. 213 



x\rt. XXTV. — Castle Bock, Coromandel. 



By J. M. Maclaren. 



[Read before the Auckland Institute, 28th Atigust, 1899.] 



The sub]ect of these few notes will be readily recalled to 

 mind by those who have had occasion to travel within sight 

 of the northern portion of the Cape Colvilie Peninsula. The 

 abrupt manner in which this peak rises from the mam range, 

 and its extremely castellated appearance, tend to make it the 

 most salient feature in an otherwise featureless landscape. 

 Situated some five miles south-east of Coromandel Township, 

 and in a low saddle on the main range, here 1,250 ft. in 

 height, it reaches an altitude of 1,724 ft., a height insignifi- 

 cant in itself, but sufficiently striking when the last 400 ft. of 

 ascent is sheer on three sides. 



To the casual observer the appearance of the peak pro- 

 bably conveys a suggestion of Titanic agencies that, in an- 

 other quarter of the globe, have once again attempted to pile 

 Ossa on Pelion. And, indeed, it must have been a mighty 

 convulsion of nature that heralded its appearance ; but at the 

 same time it is to be remembered that the present form of 

 the rock is not that which it assumed at its birth, but that 

 into which it has been moulded by the action, during the 

 ages, of the sculpturing-chisels of nature — the rain and the 

 winds. 



Though notable in itself, Castle Eock is much more in- 

 teresting as being the most prominent feature of an extrusion 

 of igneous matter that extended for miles across the coun- 

 try, from north-west to south-east, breaking indiscriminately 

 through Palaeozoic slates and slaty shales and Tertiary ande- 

 sitic lavas and tuffs. Its most northern extremity is at Kiko- 

 whakarere Bay, to the north-west of Coromandel, from whence 

 it crosses into the township, being met with in the Kathleen 

 Crown and Blagrove's Freehold Mines. Here also is a lava- 

 flow that probably issued from the fissure, flowing to the 

 west, and covering the older andesites in the Kathleen Mine 

 to a depth of 158 ft. Further to the south-east the dyke is 

 obscured by thick Pleistocene alluvial deposits, but reappears 

 on the low foot-hill north of the Tiki Creek at an altitude of 

 550 ft. In the bed of the Tiki Creek the characteristic grey 

 hornblende trachyte appears about half a mile beyond the 

 sawmill, and then, still pursuing its south-east course, crosses 

 the Pukewhau Track at an elevation of 770 ft., and is here 

 about 2 chains wide. It next reappears on the main range 

 as a knoll 1,250 ft. above sea-level, and a mile further to 



