http://gallery.usgs.gov/images/logos/usgs_only.jpg http://gallery.usgs.gov/ en-us OC_Web@usgs.gov (Office of Communications Web Group) http://gallery.usgs.gov/images/USGS.gif http://gallery.usgs.gov/ http://gallery.usgs.gov/photos/11_19_2010_cI8Lcp4BBv_11_19_2010_8 This northeast-looking photograph, on the southeastern side of White Thunder Ridge ,shows the lower reaches of Muir Glacier, then a large tidewater calving valley glacier, and its tributary Riggs Glacier. The séracs in the lower right-hand corner of the photograph mark Muir Glacier’s terminus. The ice thickness is more than 700 meters. Muir Glacier had been retreating since the mid-eighteenth century, with maximum retreat exceeding 50 kilometers. In places, more than a kilometer thickness of ice had been lost. Note the absence of vegetation and the bare bedrock faces present on both sides of the glacier. (W.O. Field)

]]> http://gallery.usgs.gov/photos/11_19_2010_cI8Lcp4BBv_11_19_2010_9 This, the first of two repeat photographs, documents significant changes that have occurred during the nine years between photographs A and B. Although Muir Glacier has retreated more than 3 kilometers and thinned more than 100 meters, exposing Muir Inlet, it remains connected with tributary Riggs Glacier. White Thunder Ridge remains devoid of vegetation. In places, erosion has removed some of the surface till. (W.O. Field)

]]> http://gallery.usgs.gov/photos/11_19_2010_cI8Lcp4BBv_11_19_2010_10 The second repeat photograph documents significant changes that have occurred during the 63 years between photographs A and C, and during the 54 years between photographs B and C. Muir Glacier has retreated out of the field of view and is now more than 7 kilometers northwest. Riggs Glacier has retreated as much as 600 meters and thinned more than 250 meters. Note the dense vegetation that has developed on White Thunder Ridge. Also note the correlation between Muir Glacier’s 1941 thickness and the trimline on the left side of this photograph. (Bruce Molnia).

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