January 25, 2019
Tic Toc Glacier (TT) and Oeste Glacier (O) in 1986 and 2018 Landsat images. Red arrow is the 1986 terminus, yellow arrow is the 2018 terminus location, purple dots the snowline.
Tic Toc Glacier at the headwaters of the Rio Tic Toc and the adjacent Rio Oeste headwater glacier Oeste Glacier are in the Parque Nacionale Corcovado of Palena Province of Chile. Davies and Glasser (2012) noted that overall glaciers in this region lost 14% of their area from 1986 to 2011. Carrivick et al (2016) reported the glaciers in the region had an average thickness of 41 m, this is relatively thin. Here we examine glacier change from 1986 to 2018 using Landsat imagery, with a 2019 Sentinel image for further visual identification of features.
In 1986 Oeste Glacier extended downvalley terminating beyond the east end of a basin, near the west end of an adjacent bedrock knob to its south. The glacier has a 3 km long, 1 km wide valley tongue fed by a higher accumulation zone to the north. Tic Toc Glacier has a terminus tongue that turns from west to north extending 800 m downvalley. This glacier has a larger accumulation zone than Oeste Glacier, the snowline in 1986 is at 1350 m the divide between the glaciers. By 1999 Oeste Glacier has retreated from the bedrock knob and a small fringing lake is developing. Tic Toc Glacier has lost much of the northern terminus tongue. The snowline in 1999 is at 1500 m. By 2016 Oeste Glacier has retreated upvalley revealing a new lake. Tic Toc Glacier has retreated out of the north trending valley that it had terminated in. The divide between the glacier is now mostly bedrock indicating it is consistently above the snowline. The snowline in 206 is above 1500. By 2018 Oeste Glacier has retreated 1700 m losing the majority of its valley tongue. It is poorly connected to the upper snowfield as revealed by both Digital Globe imagery and 2019 Sentinel imagery below, indicating the lack of a substantial contributing accumulation zone. Tic Toc Glacier has retreated 1500 m since 1986, most of its valley length. There is still a significant accumulation zone for this glacier. In both cases the majority of the valley portion of these glaciers has been lost since 1986 and the substantial divide connection has been severed. The large scale loss of these two glaciers is typical for the region as noted by the references above and by the examples of Erasmo Glacier and Hornopiren Glacier.