KAURI GUM MINING IN NEW ZEALAND 41 
considerable age. In the locality in question, the gum was so 
abundant that as much as half a ton is said to have been taken from 
twelve square feet of ground. 
Kauri gum also often occurs in swamps covering buried forests 
of kauri trees. New Zealand is a volcanic country, and frequent 
movements in the earth’s crust occur, so that many kauri forests 
which once flourished on dry ground may become partly or wholly 
submerged, and may die and eventually be buried in swamps. The 
same result may occur where a lava flow obstructs a stream, form- 
ing a lake, which inundates a kauri forest. The lake may eventu- 
ally be filled up, first becoming a swamp and then perhaps dry 
land again, inclosing the dead trees with the earthy accumulations. 
In either case accumulations of kauri gum may occur with the 
remains of the old forests. 
Considerable kauri gum is also obtained in districts from which 
the kauri lumber has only recently been cut, while some is mined 
in the soil of still standing kauri forests, and a certain amount has 
been obtained by tapping the trees, but the practices of mining in 
living forests and of tapping have been largely prohibited as 
injurious to the trees. 
The gum usually lies from a few inches to several feet in the soil 
or underlying clays and sands, though sometimes it is exposed on 
the surface. A depth of from two to four feet is common, and a 
greater depth is often encountered. On the dry uplands it is usually 
shallower than in the swamps, where it may sometimes be twelve 
feet or more in depth. It occurs in irregular lumps, from a few 
ounces to several pounds in weight, lumps of from ten to twelve 
pounds being not uncommon, and in rarer cases lumps of as much as 
fifty or one hundred pounds have been found. It is in very vari- 
able quantities in the soil, being in some places too scattered to 
work profitably, in others abundant. 
In some places successive layers of clay or sand carrying gum 
have been found, one above the other and separated by barren 
layers. Sometimes there are three or four of these gum layers and 
they represent the sites of former kauri forests which have been 
successively destroyed. The gum from each forest accumulated 
in the soil and became more or less covered with earthy matter 
