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surface to an anastomosing pattern, then to short elliptical cups and domes,
and, in extreme cases, to small crescentic corrugations, elongated more or
less perpendicular to the general direction of lineation. Such relationships
may be seen south of Jim May Creek and east of the head of Cutbank
Creek.

Several outcrops in the Tenakihi Range show a second, much less
distinct lineation. Where best observed the second lineation is approxi-
mately parallel with the fold axes of the bedding (and schistosity), in-
dependent of the direction of the more widespread lineation exhibited
by corrugations lying in the foliation plane at an oblique angle to the
fold axes.

SCHISTOSITY

All of the Tenakihi group rocks, except the purest quartzites, have a
schistose or gneissic structure determined by the parallel orientation of mica
and chlorite grains. The planes of schistosity or gneissosity are deformed
into the small ‘lineation’ crumples previously described, but in any area
larger than a few square inches, they are nearly always found to lie in
large gentle folds almost exactly coinciding with bedding structures. Over
many large areas, schistosity and bedding appear to be rigorously parallel;
and in other areas the maximum angular difference between them is less
than 5 degrees. In areas of relatively highly deformed rocks it has been
observed that the schistosity is commonly less sharply contorted than the
bedding. The general relations are such that the schistosity planes are
parallel or very nearly parallel with the major bedding structures, ‘but cut
across the bedding of the smaller folds, although exceptions to this
generalization have been noted. The plane of schistosity thus reflects the
large-scale structure of the anticlinoria in which the Tenakihi group rocks
characteristically occur, but in many places bears no relation to minor
contortions of bedding.

GENERAL FOLD STRUCTURES

The structures of individual beds in the Tenakihi group are dominated
by the major northwest trending anticlinoria already mentioned, and minor
folds can be recognized as local variations from this general pattern. The
axis of each anticlinorium is curved and undulating, ranging from flat-lying
to a northwest plunge of as much as 15 degrees; and the axial plane dips
55 to 70 degrees northeast. The individual folds forming the anticlinoria
are for the most part open and gentle, and range from 500 feet to a mile or
more from crest to crest. The anticlinorium on Chase Mountain and the
area of Tenakihi group rocks in the north end of the Butler Range are
believed to be connected by the overturned synclinorium in Tomias Lake
Valley. The synclinorium appears to be essentially isoclinal between limbs
about 7 miles apart. If this interpretation is correct, all the Tenakihi group
rocks of the Butler Range in the map-area are overturned.

ABNORMAL FOLD STRUCTURES

In addition to the relatively regular, wave-like undulations forming
the major, compound anticlines or anticlinoria of the Tenakihi group, there