The end of an ice age. Ice harvesting as an occupation.
D005519:Food Preservation / Q000266:history*; D049672:History, 19th Century; D049673:History, 20th Century; D007053:Ice / Q000266:history*; D008396:Maryland; D008404:Massachusetts; D009790:Occupations; D010414:Pennsylvania; D006113:United Kingdom
D007053:Ice