En la página web del Parque nacional de Glacier Bay (
http://www.nps.gov/glba/index.htm), cuentan lo siguiente:
In 1794, as the mother ship H.M.S. Discovery, Captained by George Vancouver, lay at anchor in Pt. Althorp, a survey crew under the command of Lt. Joseph Whidbey painstakingly maneuvered their longboats through the ice-choked waters of Icy Strait.
The remarkably accurate chart the survey produced shows a mere indentation in the shoreline, "terminated by solid compact mountains of ice," where Glacier Bay is today. The great glacier that filled the Bay
was by then in rapid retreat, and was the source of the floating icepack that so hindered Whidbey. Any visitor who came by at the glacial maximum, a few decades earlier, would have found the glacier’s tongue extending out into Icy Strait almost to Lemesurier Island.
Vamos, que cuando los de la pérfida Albión se pasearon por allí, el glaciar ya parecía que estaba en decaimiento.
Más adelante dice que en 1899 (año de la foto) hubo un tremendo terremoto que hizo que durante una década fuera muy peligroso navegar por la zona debido al hielo.
No tengo ni idea de dinámica de glaciares, pero la lógica dice que si hay un fuerte terremoto, es posible que el glaciar se deslice por la ladera.