Geological map (modified from Larsen, 1990) showing distribution of seaward-dipping reflector sequences and continental flood basalts of the North Atlantic Volcanic Province. ODP and DSDP drill sites along the volcanic rifted margins of the North Atlantic are shown. Subaerially erupted basalts show flood basalt structure landward of the inferred continent/ocean boundary and have a SDRS structure seaward of the boundary. The part of Northwestern Iceland that shows SDRS-like structure is included. Note that the spreading history of the Iceland Plateau north of the GIR is different from that south of the GIR. In the young crust north of the GIR, the typical SDRS structure is not continuously present and extends to a depth of only about 2 km. However, below the GIR itself, the SDRS may attain a thickness of 10 km (Larsen and Jakobsdóttir, 1988).