The Cobequid Hills (Unit 311), part of the Avalon Uplands, descend abruptly along the Cobequid Fault to the lowlands fringing the Minas Basin. To the north, in contrast, the Cobequids merge gradually into the Cumberland Hills (Unit 581). Headlands of basalt along the Minas Basin separate bays carved from the less-resistant Riversdale shales and Triassic sandstones of the Fundy Coast (District 710).