ABSTRACT

The California Standard Fording Mountain well penetrated the Lewis Thrust 12 miles west of its surface trace and established the existence of a major syncline and anticline in the thrust parallel to, but west of, the previouly mapped folds along the outcrop of the Lewis at Tornado Pass. The major anticline and syncline in the thrust are represented in the rocks of the hanging wall of the Lewis by the Erickson Ridge - Fording Mountain compound anticline and by the Alexander Creek syncline.

The well was drilled on the crest of the Fording Mountain anticline which is bounded on the east by a west-dipping normal fault, the Fording River fault. This normal fault may either displace the Lewis or join with it; the alternate interpretations are discussed in the light of the detailed geology of the well and it is concluded that either may apply.

The Fording Mountain well established another control point for a minimum displacement on the Lewis thrust of 12 miles as compared to zero at Mt. Kidd to the north and 24 miles at the International Border to the south.

The eastward deflection of the surface trace of the Lewis at North Kootenay Pass is believed to have been produced by an original "S" shape in the fault plane, rather than by later folding of a planar thrust.