Terminal and recessional moraines in the fjords of southern Chile

Abstract

Moraine ridges marking the outermost limit of a glacier advance are known as terminal moraines; recessional moraines indicate stillstands or minor readvances during overall glacier retreat. At the Last Glacial Maximum, the Patagonian Ice Cap advanced to fill the complex fjord system of southern Chile. Since then, ice has retreated producing recessional moraines, although tidewater glacier readvance during the cool period known as the Little Ice Age also deposited terminal moraines in the fjords. At present, the remaining smaller ice caps of northern and southern Patagonia feed just a few tidewater glaciers, which are the lowest-latitude glaciers reaching the sea at fjord heads today (Dowdeswell & Vasquez 2013). In southern Chile, a number of large sedimentary ridges have been mapped across fjord axes (Fig. 1a–e) (Boyd et al. 2008; Dowdeswell & Vasquez 2013). Iceberg Fjord at 48° 43.5′ S is an arm of Messier Fjord, located immediately west of the northern part of the 13 000 km2 Southern Patagonian Ice Cap. A prominent submarine ridge is present across the 2 km wide fjord about 3 km from the current terminus of the tidewater Tempano Glacier which drains west from the ice …