Thompson and Bradshaw sounds, Fiordland, New Zealand: a relict, mid-latitude, temperate glacier system

Abstract

Fjords are among the most spectacular glacial landforms on Earth (Holtedahl 1967; Syvitski et al. 1987; Benn & Evans 2010). New Zealand fjords are deep valleys cut into metamorphic basement rocks by former mid-latitude glaciers and flooded by seawater following glacial ice retreat (Pickrill et al. 1992). They are now ice free, 15–45 km long with maximum water depths of 200 to >400 m, and are surrounded by forested mountains rising to >2000 m. Their distinctive landscapes, geomorphology and sedimentary deposits reflect their past glaciation followed by deglaciation and marine transgression (Syvitski et al. 1987). Thompson and Bradshaw sounds comprise a single, 35 km long, 430 m deep fjord that is sinuous, very steep-sided with U-shaped morphology and is typically 1.5 km wide (Fig. 1). Precipice Cove (PC) is the only significant marine tributary, whereas a <50 m deep, rocky marine saddle joins the fjord to Doubtful Sound (DS) (Fig. 1a). Hanging valleys are common landscape features above the lower walls of the …