One of the disadvantages of traveling on short notice is the inability to research deeply into the history and offerings of a place before visiting it for the first time. For those are considering an accessible cruise in Glacier Bay here is a list of links on the natural history of the region:
Glacier Bay National Park
http://www.nps.gov/glba/
Explore-a-Park: Glacier Bay
http://www.glacierbay.org/
Alaska Magazine: Ancient Ice
http://www.alaskamagazine.com/index.php?option=com_content&task=view&id=57&Itemid=36