During the summer of 1959, a geological reconnaissance of the Lochaber area in Antigonish County (Fig. 1) was made by several of the students at the Massachusetts Institute of Technology summer camp under Boucot’s supervision. Although the structural and stratigraphic results are less conclusive then those from nearby areas, this location is geologically strategic, and it is appropriate to list some of the facts observed. A suite of sedimentary, volcanic, and intrusive rock types lying to the west of Lochaber (PL 9) is similar to those assigned elsewhere in Antigonish and Pictou Counties to the Browns Mountain Group. To the east of the rocks assigned to the Browns Mountain Group (Pl. 10), there is a sequence of greenish siltstones and slates, together with a scattering of shelly limestones, which can best be referred to as “Arisaig Group undifferentiated.” These beds have provided enough diagnostic fossils to demonstrate that they include representatives of the following: French River Formation, McAdam Brook Formation?, Moydart Formation (green member only), and the Stonehouse Formation. Table 8 details the brachiopods found in these strata. East and southeast of the beds assigned to the Arisaig Group, a sequence of siltstones and fine-grained sandstones that are predominantly reddish are assigned to the lithologically similar Knoydart Formation. The contact with the underlying Arisaig Group is gradational on Cameron Brook (Pl. 10) as well as on the two unnamed brooks to the north of it. The gradational contact consists of an interbedding over a stratigraphic interval of . . .