Lake George 61°15′00″N 148°37′00″W, a glacial lake formed near the face of the glacier, received national recognition by the National Natural Landmark (NNL) Program. Lake George was recognized because of a unique natural phenomenon called a "jökulhlaup", an Icelandic term for glacial lake outburst flood. The breakup of this ice dam would send a violent wall of water, ice and debris down the river valley causing massive flooding and sometimes devastation to local settlers' properties. The jökulhlaup occurred annually until it ceased in 1967 due to glacial recession, thought to be associated with the massive Good Friday earthquakeof 1964.