362 Transactions. — Geology. 



gneiss, and other crystalline rocks had exercised an influence 

 on the composition of the lavas and other solid products 

 erupted by the volcanoes of the central volcanic region of this 

 Island. 



In conclusion, I have to acknowledge my great indebted- 

 ness to Mr. G. T. Wilkinson, the Government Agent at Otoro- 

 hanga, who, although unable himself to accompany me, with 

 much forethought made all necessary arrangements for my 

 guidance and conveyance to the desired locality. To his 

 kindly action in sending the rocks to the Thames on behalf of 

 the native owners of the land are due the circumstances which 

 led to my identification of the granitic rocks ; and for this 

 also I have to thank him. I have also to gratefully thank 

 my friends Mr. Charles King and his wife Hana Taare, Mr. 

 Arthur Ormsby, Eawiri te Hauparoa, Horopapera, and Te 

 Kapuranga (the daughter of Hoponi), for their escort to the 

 Turitea, and ready assistance in helping me to investigate the 

 problem surrounding the rare occurrence of granitoid rocks 

 in that locality. 



Art. L. — The Earthquake of the 4th December, 1891 : Notes 



thereon. 



By George Hogben, M.A. 



[Read before the Philosophical Institute of Canterbury, 2nd June, 1892.'] 



Plate XLVI. 



During last year (1891), Dr. Lemon, Superintendent of Posts 

 and Telegraphs, kindly made special efforts to obtain for me 

 from a number of stations round Cook Strait exact records of 

 earthquake-shocks. The first fruit of those efforts was the 

 attempt in a previous paper to find the origin of a small earth- 

 quake on the 5th July, 1891. The facts of the earthquake 

 now under discussion are, however, considerable enough to 

 deserve a somewhat fuller treatment. It will be seen that the 

 data are still insufficient to determine the depth of the origin, 

 for the estimate of the depth given below can only be regarded 

 as very rough indeed. I think we are justified in saying that 

 we now know the position of one of the chief sources of the 

 Cook Strait shocks. 



