64 The N.Z. Journal of Science and Technology. [April 
lateritization is only possible on a land-surface approaching penep]anation, 
an extremely local condition in a young volcanic island. 
The following is the list of the minerals recorded from Western Samoa, 
the majority being determined microscopically in the course of petrographic 
study of the rocks : Aegirine, aenigmatite, augite (and titaniferous augite), 
apatite, aragonite, biotite, bronzite, calcite, chlorite, enstatite, feldspars 
(bytownite, labradorite, orthoclase, and sanidine), gypsum, haiiyne, kaolin, 
magnetite (and titaniferous magnetite), nepheline, olivine, opal, serpentine, 
and sulphur. 
Sedimentary Rocks and Coral Reefs. 
Coral reefs, mostly of the barrier type, are well developed in Samoa, 
but by no means form continuous girdles to the islands. The reefs 
are interrupted by passages opposite every important stream, no doubt 
primarily owing to the deleterious effect of fresh water on the coral 
organisms. It is generally assumed locally that the absence of a reef and 
the presence of an “iron-bound” coast is an index of the recent volcanic 
character of the coast rock. This is certainly true in many parts of Savaii, 
but is by no means always the case in Upolu. The height of the cliffs on 
many promontories alone shows a considerable geological age, if the forma¬ 
tion of the cliffs is due to wave-cutting alone. Drowning of the coasts by 
depression and downfaulting of parts of the coast, carrying the reefs down 
with them, and depressing the shore platform below the depth at which 
reef-building corals can grow, are probably important causes of many of the 
steep coasts not bordered by reefs. Downfaulting seems the best explana¬ 
tion of the steep-walled harbours like Fagaloa Bay, which shows soundings 
of 40 fathoms at its mouth ; the absence of valleys behind precludes an 
explanation of the harbour as a simple drowned valley, and there are no 
crater-like features. 
Along the lower coasts of the islands bordered by barrier reefs there 
are stretches of country where a thin level layer of coral sand covers an 
uneven surface of volcanic rock. The beaches of the bays are composed 
of sand, with volcanic rocks outcropping at the points. These coral-sand 
coastal plains form the well-populated districts, such as, to name only some 
of those I saw, Salealua (Matautu) and Fa’asalele’aga in Savaii, Aleipata 
and Salufata in Upolu. An elevation of the shoreward part of the lagoon 
might have given rise to such coastal plains; but this cannot have taken 
place, since the reef itself is not raised, and could hardly everywhere have 
been cut down by wave-action. Islets within the lagoon would certainly be 
abundant. Friedlander suggests that the coral sand has been blown inland 
by the wind. The narrowness of the sand-plains and their constant 
proximity to the sand-beaches are in accord with this hypothesis. Two 
difficulties are that there are rarely, if ever, any sand-dunes, and that I 
never once observed the wind raising the sand on the beaches. Tidal waves 
might play a part in transporting the sand, but they would need to be at 
least 6 ft. high, since the sand-plain is generally this height above sea-level. 
The tidal waves recorded at Matautu by Mr. Williams in 1906 and 1907 
during the Matavanu eruptions reached as much as 10 ft. or 12 ft., but 
seldom coincided with high tide. They were felt at Apia, but did not 
there exceed 1 ft. 
A peculiar beach-formation is often seen along such sand-beaches, con¬ 
sisting of a well-stratified limestone, following in strike the curve of the 
beach, and dipping at about the same angle as the beach seaward (fig. 2). 
