Alaska – Matanuska. Thoughts about the frontal moraine

June 8, 2015 in @en, focus-en

The most recent frontal moraine pushed by the Matanuska glacier (Alaska, USA) appears as an unsorted till mound with relatively recent vegetal cover (Figure 1). Opposed to it, in the lowest areas of the ablation moraine, the till is generally reworked by the dynamic hydrological processes of the thawing glacier. This glacier and ablation moraine complex is still active, and is a good site to observe the contemporary land forms that became relict at the Beaver Creek study site (Yukon).

matanuska

Figure 1: Overview of the frontal moraine (Matanuska glacier, AK)

Thermokarst landscape, Interior Alaska near Fairbanks.

November 4, 2014 in post

Yedoma deposits (Late Pleistocene sedimentation and freezing in unglaciated areas) are extremely ice-rich. Over time thermokarst modifies the landscape to trigger the developments of various landforms, here along and in an alluvial plain with meandering river. In this picture, we can observe several thermokarst lakes, some of which were drained, thaw ponds, peatlands, peat edge along lake margins, and collapsed bogs (Photo D. Fortier © Geocryolab). Fluvial activity plays a role in the life-cycle of these aquatic thermokarst ecosystems, draining ponds and lakes as rivers meander. Thermokarst landscape can play an important role in the climate system by releasing carbon sequestrated in the permafrost back to the atmosphere via oxidation and microbial activity.

 

Interior

Thermosyphons (Alaska)

October 28, 2014 in post

Thermosyphons are closed-system heat extraction devices. Installed in the permafrost they contribute to cooling of the ground and maintaining the permafrost intact. Although thermosyphons are effective mitigation techniques, their cost currently limit the possibility to deploy them extensively along linear transportation infrastructure such as road but have been used with success to mitigate heat island under buildings over permafrost. Geocryolab is involved in testing the effectiveness of thermosyphons using high-resolution   infra-red camera and ground temperature.

 

themosyphon 1

Thermosyphon installed in the muskeg at an experimental site of interior Alaska near Fairbanks (photo M. Kanevskiy, © Geocryolab)

 

 

 

 

 

 

 

 

 

 

themosyphon 2

Black and white image from FLIR infra-red camera showing thermosyphon temperature (15.9°F = -9°C) and air temperature (-40°F = -40°C) (photo M. Kanevskiy, © Geocryolab)

 

 

 

 

 

 

 

 

 

 

 

themosyphon 3

Infra-red thermal image of thermosyphons in the natural setting. The reddish color (warmer than surrounding terrain) indicates the thermosyphon is extracting heat from the permafrost (photo M. Kanevskiy, © Geocryolab).