Here's what one of them said, Art:

Although the Athabasca and Dome glacier at one time coalesced, the Dome glacier has not receded as significantly due to the presence of an insulting moraine cover (Ommanney, 2002). From 1875 to 1919 the glacier receded 530m and 318m from 1919 to 1953. Between the terminal moraine remnants and the present ice front, four recessional moraines appear (1900, 1908, 1913, and 1918) (Ommanney, 2002).

Don't know if that explains much, though.