Hill. — On Distribution of Pumice. 297 



surface rocks belong to the later Tertiary or Pliocene and the 

 Post - tertiary formations. These later deposits cover an 

 enormous area inland, extending from Napier in a north-west 

 direction beyond Pohui, on the Taupo Eoad, and in a west and 

 south-west direction through the Heretaunga and Kuataniwha 

 Plains, and thence onward and through the Seventy-mile Bush 

 as far as the Manawatu Gorge. Similar rocks cover a large 

 extent of country in the Poverty Bay District, and extend inland 

 from Gisborne in a south-west direction as far as Te Kapu, 

 near Wairoa or Clyde, although not so shown on the geological 

 map. From specimens of fossils lately received from Mr. 

 Balfour, sheep-farmer, who resides in the middle basin of the 

 Mohaka Biver, it would seem that similar young rocks are 

 largely developed in that district also ; and hence a continuous 

 belt of later Tertiary and Post-tertiary deposits can be traced 

 through the East Coast District for a distance of nearly 200 

 miles. Westward, beyond the younger Tertiaries and Post- 

 tertiaries, lie the Buahine and other mountains of the central 

 chain, the rocks of which belong to the older Mesozoic and 

 Palaeozoic formations. Now it is a curious circumstance that 

 over by far the larger portion of the district under notice traces 

 of pumice are to be met with, either upon the surface or imme- 

 diately below the dark soil, which in a former paper I referred 

 to as being partly of volcanic origin, and which covers a large 

 part of the country in the Hawke's Bay District. This pumice 

 is found as a surface -pumice equally upon the summit of the 

 Buahine Mountains as upon the Napier Hills, or upon the hills 

 extending between Napier and Tologa Bay. Neither the surface 

 irregularities nor the rock formations have made any difference 

 in the distribution of the pumice over such a wide area. On the 

 top of the Buahine Mountains the pumice is in the form of large 

 pebbles, such as are now to be found in immense deposits on 

 the Kaingaroa Plain, in the Taupo District, and similar to those 

 which are brought down and deposited along portions of the 

 Napier beach by the Ngaruroro and other rivers. Much of the 

 pumice underlying the surface-soil is of the character of grit, or 

 coarse purnice-sand, although in many places the pumice is as 

 fine as the finest flour, and as white as snow. 



As far as I can gather, there are three very clearly defined 

 periods of pumice deposition. These are : — 



(a.) A surface or subsoil deposit of comparatively recent 

 age, and referred to above as covering most of the 

 country to the west, north-west, and north of Napier ; 

 (b.) A Pliocene pumice deposit of vast extent and thick- 

 ness, interbedded with shingle, clays, lignite, and 

 fossiliferous sands ; 

 (c.) A Cretaceo- tertiary ? (Miocene) pumice deposit, found 

 interbedded with the blue-clay marls. 



