Sentence:  As you mount the Aletschhorn from the sleeping place, towards the lowest col from which you first overlook the Lotsch Glacier there descends, from a higher plateau, and on your right hand, a large mass of <WSD>sérac</WSD>. 
Meaning of the word marked with <WSD> tags:  A sharp tower of ice formed by intersecting crevasses of a glacier. (from mid 19th c.)