A group of related mafic dykes is present along the eastern shore of Nova Scotia from Halifax to Country Harbour. The dykes are generally vertical, strike about 150°, and have an abundance of carbonate, apatite, and hydrous mafic minerals, indicating that the dykes may have formed from an alkaline (lamprophyric) magma. They postdate the Acadian folding of the Cambro-Ordovician Meguma Group metasedimentary rocks but predate Carboniferous faulting. Abundant exotic gneissic and (meta)plutonic xenoliths, representing probable pre-Meguma Group rocks, are found in half of the presently known dykes.The dykes may have formed in a regional tensional field during a shearing event synchronous with docking between the Meguma and Avalonian terranes or in a more local radial stress field around an igneous body, such as the Bog Island Lake or Ten Mile Lake diatreme in the Liscomb Complex. Similar ages suggest that the dykes may be related to the intrusion of the Devono-Carboniferous granites of the Musquodoboit batholith.