Cores of the bedrock underlying the southeastern Baffin Island shelf were recovered by underwater electric rock core drill at four localities. Cores from three of the localities consist of olive gray to dark yellow–brown slightly dolomitic limestones, in part burrowed and containing flat pebble conglomerate and breccia. Fragments of trilobites, brachiopods, crinoids, and other fossils including coral are present. Radiolarian wackestone was found at one locality where the rock also contains finely disseminated organic material. The strata have been assigned an Ordovician age (Caradoc) based on identification of chitinozoa, scolecodonts, and coral material. Depositional environments included shallow intertidal–subtidal, open shelf, and outer littoral–epibathyal. Core from the fourth locality is Precambrian biotite gneiss.Seismic reflection and magnetic profiles have been used for correlation of the corehole data and to outline the geology of part of the southeastern Baffin Island shelf.