Hill. — On Volcanic Diist-ahoivers. 385 



Art. XLIX. — Traces of Volcanic Dust -showers at Napier, Petane, 

 and generally thiviighout the East Coast Districts, Noi'th of 

 Cape Kiibiappers. 



By H. Hill, B.A. 



[Read before the Hawke's Bay Philosophical Institute, 12th July, 1886.] 



The results of some recent experiments made by me upon the 

 dark soils covering the Napier and Petane Hills, as also upon a 

 dark sand deposit near Mr. Villers' hotel at Petane, may not 

 prove uninteresting to members of this Society. For some 

 time past I have been collecting data as to the extent and 

 character of the pumice deposits of the East Coast District 

 between Poverty Bay and the Manawatu Gorge, in the Seventy- 

 mile Bush. Within this wide area there is ample evidence of 

 comparatively recent volcanic products ; but until examining 

 specimens of the ejectamenta of the recent eruptions at Tara- 

 wera, in the Lake District, the thought had not occurred to me 

 that possibly there might be evidence in our Napier hills of dust 

 showers similar to those which have been experienced in the 

 district extending from Tologa Bay to Tauranga, including the 

 whole of the Bay of Plenty. 



The Napier hills, or, at least, those portions of them that 

 have not suffered from extreme denudation, are covered with a 

 remarkable cap of what at first inspection seems to be a dark 

 vegetable soil. When first broken up this soil is very produc- 

 tive ; but this quality quickly disappears unless manures are 

 plentifully used, there being little or no " body" in the soil. I 

 had often wondered how such a cap of black soil came to be 

 formed upon the hills, for only a small percentage is of vegetable 

 origin ; but on seeing several specimens of the volcanic dust 

 and sands which fell vipon the deck of the " Southern Cross," on 

 her way down from Auckland at the time of the Tarawera erup- 

 tion, the thought at once occurred to me that possibly the black 

 soil of Napier and surrounding district might be the result of 

 similar showers of volcanic dust, at a time when the volcanic 

 cones of Euapehu, Ngauruhoe, Tongariro, Tauhara, and otbers 

 were in a condition of activity. The results of my tests confirm 

 this opinion ; for I find that among the many tests I have made 

 of the soils in and around Napier, a very large percentage, in 

 fact the greater portion, are of volcanic origin. 



My experiments were carried out in the following manner : 

 I obtained from the edge of the Napier Blufl*, and immediately 

 underlying the turf, a small parcel of black soil, contaming 

 altogether about 20 ounces. This I moistened with water, and 

 made up into a kind of paste. I then arranged five different 

 receivers, one inside the other, so that the overflow of water 



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