V SOLEVU BAY 77 



second rock to be noticed is a slightly altered compact basalt 

 without olivine forming apparently a dyke near the coast about 

 half way between the village of Solevu and Ua-nguru Point. It 

 has a specific gravity of 2'84, the felspar lathes ("15 mm.) presenting 

 a marked flow-arrangement, whilst there is a fair amount of altered 

 residual glass in irregular spaces, a millimetre in size. The rock, on 

 account of its joint-structure, could be easily worked as a building- 

 stone. It is referred to genus 16, species B, of the augite andesites. 

 The hill of Koro-i-rea, which rises on the east side of the bay 

 to a height of 850 feet, has a ridge-shaped summit. Its upper 

 half is composed of a bluish-grey rock looking like a phonolite and 

 usually compact, except at the top of the hill, where it is a little 

 scoriaceous. It has, however, a specific gravity of 2-gi or 2-g2, 

 and is in fact a pretty grey olivine-basalt studded with small 

 olivine crystals about a millimetre in size and showing no other 

 phenocrysts. This type of olivine-basalt occurs also at Ulu-i- 

 ndali on the east side of Wainunu Bay, but is rare in the island. 

 It differs amongst other features from the porphyritic olivine- 

 basalts of the northern part of Seatura and of the Seatovo range 

 in the absence of plagioclase phenocrysts. There is apparently no 

 interstitial glass, whilst the average length of the more or less 

 parallel felspar-lathes is -13 mm.^ On the lower slopes of the hill 

 the common blackish porphyritic basalt or basaltic andesite is 

 exposed. In the grey-basaltic upper portion of this hill we have 

 probably an old volcanic " neck." 



Following the line of hills inland from Koro-i-rea, we cross the 

 intervening saddle 450 feet above the sea, and ascend the slopes of 

 Koro-tolutolu, a ridge-shaped mountain backing Solevu Bay, and 

 having, as its name indicates, three peaks, of which the highest is 

 1,280 feet above the sea. My observations indicate that this moun- 

 tain is formed in mass of the common blackish-basalts described 

 under genus 37, their specific gravity being 2-88 to 2-94. But Koro- 

 tolutolu has also the peculiarity that it appears to be in mass 

 magnetic. The rocks obtained from its summit, half-way up its 

 western slopes, and near its foot on the same side, all display 

 polarity, a character also of the rocks of the neighbouring hills of 

 Ulu-i-matua and Koro-i-rea, but in their cases seemingly confined 

 to the higher levels.^ 



Neither tuffs nor agglomerates came under my notice at Solevu 

 Bay. This appears to be an ancient corner of the island, from 



1 Referred to genus 16 of the olivine-basalts. 

 ^ This subject is discussed in Chapter XXVI. 



