45

Very little crumpling, or swelling and pinching of beds, is found in the
Tenakihi group rocks, probably because of their strong, competent nature
and the regular, large-scale folding to which most parts of the group have
been subjected. There is probably some thickening, particularly of the
schist beds, at the crest of the anticlinorium, although the change in thick-
ness in beds between crest and limbs of the large folds is imperceptible in
the field; consequently, the thickness of the lowermost beds of the measured
sections may be slightly too great.

DETAILED SECTIONS
Generalized Section in the Tenakiht Range

The Tenakihi group rocks in Tenakihi Range may be conveniently
divided into conformable units, of distinctive lithology or repetitions of
lithological sequence, whose thickness, measured in the field, ranges from
60 to more than 1,500 feet. The boundaries between the units are in part
arbitrary, and there may be, in some instances, as much variation within a
unit as there is from unit to unit. Microscopic study of representative
specimens from each unit shows a relatively regular change in the kind and
abundance of porphyroblasts, and in the composition of the groundmass,
with successively higher stratigraphic units.

Overlain by Ingenika group (See stratigraphic section page 75)

Top of Section Thickness
Feet

Quartz-biotite-muscovite-chlorite _ schist, silver-green, crumpled, sparingly
garnetiferous; interbedded with and grading to quartzite, sugary, mica-

aceous; beds 4 foot to 3 feet thick; includes a total of 300 feet not exposed 1,320
Quartz-biotite-muscovite-chlorite schist, smooth, platy to finely crenulated, with
irregular porphyroblasts up to 8 mm. in diameter forming in clusters of

chlorite grains, and a few large grains of INALNSHILCM Me rte eienslelaletelaiaewlaiciers 380
Quartz-muscovite-biotite schist, sliver-grey-green to rusty grey, moderately
coarse-grained, crumpled, strongly porphyroblastic, with dark brown to

black subhedral garnet porphyroblasts up to 2 em. in diameter .......... 190

Phyllite, silver-grey, finely crumpled, sparingly garnetiferous........+-.-+-+++- 220
Quartz-biotite schist, garnetiferous, silver-green ; interbedded phyllite, lustrous
silver-green, crumpled, containing minute euhedral garnet porphyroblasts in

a quartz-biotite groundmass ....-..-- 1. eee e eect eee eter e eset 140
Quartzite, feldspathic, pale silver-green, banded, containing minor chlorite(?)
and amphibole; interbedded quartz-biotite schist, garnetiferous, grey-green 410

Quartz-mica schist, garnetiferous; interbedded quartzite, slightly garnetiferous,
light grey, schistose, partly gneissic, with clusters of epidote grains accom-

panying garnet porphyroblasts ........++-eessseee eerste ete e este esses 1,580
Quartz-mica schist, garnetiferous, kyanite-bearing; about 25 per cent inter-
bedded quartzite, feldspathic, slightly garnetiferous, SCHISLOSE | ae clei elelate iets 1,390

Kyanite-garnet schist, silver-coloured, porphyroblastic, with kyanite, garnet,
and lesser staurolite porphyroblasts in a biotite-muscovite-chlorite-quartz

BLOUNUMASS ..-.. 2-22 e cece eee rene eee e cess eee testes ects tsetse eeenens 150
Quartz-mica schist, garnetiferous, grey-brown to silver-grey; about equal
amount of interbedded quartzite, slightly garnetiferous, micaceous ........ 200

Garnet-mica schist, crumpled, with corroded garnets up to 3 mm. in diameter
composing as much as 20 per cent of the rock; minor quartzite, thin-
Lael uicis succosdehuseudHs ooenUodoosD oDaanUonODoSNUdUuEDcoopUDoAOnoNS 420

grey, in beds 1 foot to 3 feet thick .............-+eeeeee eect ere e nett eens 580