The Seismic Record of Glaciation in Nachvak Fiord, Northern Labrador

Nachvak Fiord is a 45 km long glacial trough in the Torngat Mountains of northern Labrador, Canada (Fig. 1). The fiord is 2 to 4 km wide, increasing gradually eastward to Nachvak Bay, which opens to the Labrador Sea. The sidewalls are generally steep, rising in places 1000 m vertically from sea level. Bathymetry reveals a succession of basins, four of which occur between Tasiuyak Arm and Nachvak Bay (Fig. 1). Maximum water depths in the four basins are 90, 160, 170, and 210 m from west to east. The four basins are separated by shallow barriers between 10 and 180 m below sea level. Two of these, at Kogarsok and Tinutyarvik, have many of the characteristics of riegeln or glacial steps. The fiord threshold at the entrance to the fiord is very shallow with an average depth of <50 m and numerous bedrock-cored shoals.