Glacial Movement

I an currently teaching a geology lab for the first time, which has its challenges, but I since I have been rockhounding as a hobby for much of my life it has also been fun and educational.  I have been looking at older topograpic maps and aerial photos of various alpine glaciers and comparing them to more recent information and found that while some of the world's glaciers have advanced, many have been retreating. The picture shows an aerial photo of a Alaskan glacier taken in the 1950's in comparison to a more recent image on Google Earth. This is one of those glaciers in retreat.