• The Cape Phillips Formation was introduced by Thorsteinsson (1958) for a sequence of dark grey to black shale, calcareous shale, and minor argillaceous limestone, representing a graptolitic basin facies, with its type section located at Cape Phillips, northeastern Cornwallis Island. It was estimated to be about 3000 m thick (Thorsteinsson and Kerr 1968) and was divided into three members (Thorsteinsson 1958). The lower, Member A, comprises mainly dolostone, argillaceous limestone, fetid shale, and cherty argillaceous limestone. The middle, Member B, conformably overlies Member A and is composed mainly of cherty argillaceous limestone, argillaceous limestone, cherty calcareous shale, and calcareous shale. The upper, Member C, consists of an extremely monotonous succession of alternating calcareous shale, argillaceous limestone, limestone, and shale. Member C accounts for roughly three-quarters of the formation’s total thickness. Based on graptolite biostratigraphy, the formation was assigned a Middle Ordovician to Late Silurian age (Thorsteinsson 1958), and later modified to Late Ordovician (Ashgill) to Early Devonian (Gedinnian) (Kerr 1976; Mayr et al. 1998). More precise correlations were made by Melchin (1989), in which Members A, B, and C ranged from Late Ordovician to middle Llandovery, early to latest Telychian, and latest Telychian to Ludlow, respectively.