198 group strata against rocks of the Wolverine complex, and Wolverine com- plex rocks derived from the Ingenika group against those derived from the Tenakihi group. The late Paleozoic rocks and the Uslika formation in the southeast part of the map-area have been offset by a tear fault along Osilinka River Valley. This fault has carried the structures on the west side about a mile to the north relative to those on the east. The tear fault has offset the faults that have emplaced the Uslika formation and the diagonal and small longitudinal faults in the late Paleozoic rocks, but has been itself truncated by the major longitudinal fault that forms the boundary between late Paleozoic and Ingenika group rocks. LONGITUDINAL FAULTS Steeply dipping, through-going, subparallel longitudinal faults, so called because they trend parallel with the regional structure, have recorded the last important deformational movements in the map-area. The largest of these faults divide major rock units or older structures. It is probable that movement has occurred along most or all of them at several different times, but a large part of the movement has post-dated one or more periods of earlier, though post-Paleocene and later than the last folding, faulting. The direction of movement on these faults has probably been complex, and it is rarely possible to locate faulted extensions of older transverse faults or of folds. The net movement appears, however, to have been mainly vertical, and although evidence is scanty, most faults appear to have the characteristics of high-angle thrusts rather than normal faults. Two of these longitudinal faults form contacts between major map- units. One brings Takla group rocks on the southwest against late Paleo- zoic rocks to the northeast. The crustal movements represented by this fault may be connected, through the subparallel faults in the southeast corner of the map-area, with those of the Manson fault zone (Armstrong, 1949, p. 118). The other, which may be an extension of the Wolverine fault to the southeast (Armstrong, 1949, p. 119), brings late Paleozoic, including Cache Creek group, rocks on the southwest against Ingenika and Tenakihi group strata to the northeast. Where exposed, these faults are sheared and schistose zones up to several hundred feet wide, and are generally accompanied by subsidiary, more or less parallel faults, com- prising a disturbed zone as much as 1,500 feet across (See Plate VIII A). The Omineca fault (Lord, 1948, p. 50) or Pinchi fault zone (Armstrong, 1949, p. 117), a major structure extending more than 200 miles from Carp Lake map-area (Armstrong, Tipper, and Hoadley, 1947) to McConnell Creek map-area, passes through Omineca River Valley in the southwest corner of Aiken Lake map-area. At this place it forms the contact between the Cache Creek group and the Hogem batholith. A fault of slightly different character appears to diverge from the thrust in Pelly Creek Valley (part of the ‘Pelly Creek lineament’), down the line of the canyon near the mouth of Pelly Creek. Shearing on the canyon walls suggests that the latest movement was one in which the west side moved down and to the south, with respect to the east side. This fault may join with the fault zone in Swannell River Valley east of Mount Lay.