The Trench prospect crops out immediately southwest of the Ecstall South Lens (1) (See Ecstall 103H 011). The showing is exposed by a large open cut near the base of the hill immediately north of the old mining camp, and 140 metres east of the Main Adit portal (Hassard et al., 1987a, Figure 6). In the exploration trench, quartz-sericite schist hosts a north-trending 10-centimetre-thick sulphide bed. A sample assayed 330 ppm copper, 1200 parts per million zinc, 46 parts per million lead, 4.5 parts per million silver and 70 parts per billion gold (Hassard et al., 1987a, p. 26).

This same thin massive sulphide bed crops out again uphill directly to the north of this trench where it was termed the Southwest Shear (Douglas, 1953, p. 21 and 28). This showing is a 25-centimetre-wide band of massive pyrite hosted in quartz-sericite schist, and was investigated by a cluster of small prospecting pits to the west of the South Lens, 120 metres south-southwest of the portal of the Dunsmuir Tunnel, along the claim boundary between the Bluestone and the Red Gulch mineral claims. This same sulphide zone was intersected again in the Main Adit, mid-way between the portal and the No. 1 crosscut, and was also intersected in underground drillholes 60 and 60a, which were drilled southward from the east end of the No. 1 crosscut (Douglas, 1953, p. 21). The Trench/Southwest Shear prospect is significant because it indicates good potential for an en echelon lens of mineralization to the southwest of the South Lens.

The new structural interpretation that the Ecstall South and North sulphide lenses are repetitions of a single sulphide horizon on adjacent limbs of an isoclinal fold, also suggests that the Trench (Southwest Shear) mineralization may be the folded continuation of the Five Foot Vein (103H 089) prospect that crops out east of the Ecstall North Lens (103H 011).