^90 PROF. P. MARSHALL OX THE SEQUENCE OF [Dec. 1Q14, 



pale-green microlites, 1)4 X "01 mm., 39 per cent.; magnetite, 

 '025 Him., 14 per cent. 



(15) Basalt. — There is a patch of oligoclase-crystals 5 mm. in 

 diameter ; augite-ciystals rather infrequent ; olivine practically 



absent. 



Ground-mass : microlites of oligoclase-andesine constitute 55 

 per cent. : they measure '4 x '07 mm. Pale-green granular augite, 

 *04 X '012 mm., forms 34 per cent., and magnetite-crystals. '012 in 

 diameter, make up the balance of 11 per cent. There is a con- 

 siderable quantity of bright-green serpentine and a small quantity 

 of a reddish-brown, strongly pleochroic hornblende, which occurs 

 interstitially, and may be original. 



(14) Phonolite.— ISTo phenocrysts. Felspar and nepheline 

 appear to be present in about equal quantity. The felspar is 

 sanidine in rather small microlites, 2 X '03 mm. The nepheline 

 occurs in small rectangles, and is quite fresh. Each of these minerals 

 constitutes about 25 per cent, of the rock. iEgirine-augite of a 

 granular nature forms 24 per cent., and cossyrite the remaining 

 18 per cent. There is a little magnetite and apatite. The cossy- 

 rite occurs in mossy growths. 



(13) Kaiwekite. — Large crystals of anorthoclase measuring 

 5x2 mm. are fairly numerous. They are usually corroded, and 

 contain a large number of inclusions, mostly segirine. Augite- 

 erystals are mostly of the violet titaniferous variety, showing dis- 

 tinct pleochroism. Usually they have a greenish border of segirine- 

 augite, which contains a large quantity of magnetite. In the case 

 of one crystal 1 mm. wide the green border is '08 mm. wide. 

 Hornblende in hand-specimens very large, but in sections only 

 small crystals have been intersected. It is a dark-brown variety, 

 probably barkevikite, has a wide resorption-border, and occasionally 

 encloses purple augite. Olivine rather frequent, 1 x "5 mm., and 

 very much corroded. 



Ground-mass : small microlites of felspar (probably oligoclase) 

 constitute about 80 per cent. They measure "02 x '001 mm. 

 Small, short augite-crystals of irregular size make up 15 per cent., 

 and the remaining 5 per cent, consists of magnetite. Short broad 

 crystals of brown augite are common. 



(12) Basalt. — Phenociysts of acid labradorite are common, 

 measuring 1 '5 x 1 mm. Augite -crystals infrequent, brown, 1*7 X 

 1*2 mm. Olivine scarce, '3 mm. 



Ground-mass : acid labradorite, 2 x •04 mm., 55 per cent. ; pale- 

 green augite, '08 x '02 mm., 28 per cent. : magnetite '02 mm., 

 1 7 per cent. 



(11 J Basalt.- Felspar-phenocrysts of labradorite small, l'5x 

 1 mm. Augite-crystals much larger than those of the other 



