PLEISTOCENE— RECENT PLIOCENE 
454 
PACIFIC SCIENCE, Vol. XXII, October 1968 
LEGEND FOR OFU AND OLOSEGA ISLANDS 
CALCAREOUS SEDIMENTS 
Modern beaches (Qb) composed of 
unconsolidated fragments of marine 
organisms. Beachrock is frequently 
present . 
< 
Qa 
Q m 
NON CALCAREOUS SEDIMENTS 
Alluvium (Qa), including talus, 
landslide debris at the base of 
cliffs, and stream deposits. In 
areas behind constructional benches 
marshes (Qm) sometimes occur. 
Nil'll FORMATION 
Palagonitized lapilli tuff (Qnt) forms 
Nu'utele and Nu' usilaelae islets. A few 
Recent(?) flows (Qnl) of hawaiite and oli- 
vine basalt may fill former deeply eroded 
stream valleys on western Ofu. 
MAJOR EROSIONAL UNCONFORMITY 
< 
TUAFANUA FORMATION 
A' of a (Ttae) and Sili (Tts) coalescing 
shields comprised of olivine basalt, basalt, 
picrite-basalt , and hawaiite flows with a 
few intercalated beds of ash, tuff, and 
breccia. These shields and the Fatuaga 
breccia cone are intruded by numerous dikes. 
Within A' ofa caldera volcanic deposits 
(Ttai consist of thick ponded flows of 
olivine basalt, hawaiite, and ankaramite 
and a buried cinder cone. 
Tac 
Ta s 
Tot 
Tafb 
/Taf 7 
Tam 
ASAGA FORMATION 
Older cones approximately aligned along 
the regional rift zone, including a breccia 
cone (Tafb) with an associated plug (Tafi) 
at Fatuaga Point, a composite cone (Tat) at 
To'aga, a tuff cone (Tam) at Maga Point, a 
tuff cone (Tas) at the west end of Samo'i, 
and a cinder cone (Tac) at Tauga Point. 
