1921.] 
Thomson.—The Geology of Western Samoa. 
61 
Hanging from the roof may often be observed stalactites, which are com¬ 
posed of re-fused lava fluxed by the burning of the inflammable gases 
discharged from the lava flowing below, and young tunnels also have 
stalactites on the walls, and coatings of soluble salts, chiefly sulphates. 
The presence of such hollow spaces would lend themselves admirably 
to ore-deposition if the rocks enclosing them either contained the more 
valuable metals in sufficient quantity, or the area came later under the 
influence of metallogenetic gases or solutions. In discussing this aspect 
with I)r. Jaggar, of Kilauea, he surmised that the lava-tunnels were not 
very permanent features, and were probably filled with lavas from later 
eruptions, giving rise to intrusive bodies of pipe-like form. In Samoa, 
however, this does not seem to have been the case, and in the extinct 
lava-flows, both of Savaii and Upolu, lava-tunnels are of fairly frequent 
occurrence. They have, however, been considerably modified by the 
falling-in of rock from the roof and sides, and have lost their original 
nearfy circular and very regular cross-section. 
I examined an old tunnel at Falemauga, Upolu, a plantation about ten 
miles south of Apia, and about 1,300 ft. above sea-level. The rock is a 
scoriaceous basalt with the typical pahoehoe type of vesiculation, and is 
densely wooded, with a fair soil. The tunnel is approached by a downbreak 
in its course, and lies 20 ft. to 30 ft. below the surface. It can be followed 
to the south for a few yards only, but to the north for about 500 yards, 
when it is finally blocked by a large downfall from the roof. The tunnel 
is no longer in a primitive state, owing to the falling-in of the roof and 
sides, and varies from 20 ft. to 30 ft. in width, and in height from 5 ft. 
to 25 ft. Nowhere do the roof and sides seem to be the original ones, 
and lava stalactites are absent. There are, however, small stalactites, lin. 
to 2 in. long, of a soft white earthy material, evidently arising from the 
weathering of the superincumbent rock. 
There are features of historical interest attaching to this and other 
Samoan lava-tunnels. The fallen rock has all been carefully stacked into 
terraces about the size of a single or double bedstead, generally on each 
side with a pathway in the middle. The floors of the terraces are composed 
either of large flat stones carefully bedded in or of quite small material, 
so that with mats they would be as comfortable to sleep on as the floor of 
an ordinary Samoan fcde. Besides the evidence of human workmanship 
in the building of the terraces I found rare fragments of very tender marine 
shells and of charcoal, while the former German owner of the plantation, 
Herr Schroder, obtained at least three stone adzes from the tunnel, which 
he left behind, carefully labelled, in his house. I estimated that at least 
one hundred Samoans could have slept in the cave. The length of time 
that has elapsed since the occupation is shown by the fact that many of the 
terraces are now quite uninhabitable owing to drips from the roof, and are 
covered with a deep red slime, which has obviously come from the roof. 
Quite probably this tunnel was used as a hiding-place during the Tongan 
wars. 
Yon Bulow describes what must have been a similar occupation of a 
lava-tunnel near Paia, an inland village on the northern side of Savaii. 
This "tunnel is known as o le ana o le nuu le tau (the cave of the non¬ 
fighting tribe). During the war of the rest of the island with Safune (taua 
o le faitasiga a, Safune), about the end of the eighteenth century, the tunnel 
was used as a refuge, and taro and banana were stored there. The tunnel 
is described as being 7 m, broad by 5 m. high. 
