s ▁writers ▁Category : De ath s ▁from ▁cancer ▁in ▁Pennsylvania ▁Category : Pe ople ▁from ▁Ch ester ▁County , ▁Pennsylvania ▁Category : Pe ople ▁from ▁Port sm outh , ▁Ohio ▁Category : W rit ers ▁from ▁Pennsylvania ▁Category : American ▁women ▁writers <0x0A> </s> ▁An ▁ice ▁w edge ▁is ▁a ▁crack ▁in ▁the ▁ground ▁formed ▁by ▁a ▁narrow ▁or ▁thin ▁piece ▁of ▁ice ▁that ▁measures ▁up ▁to ▁ 3 – 4 ▁meters ▁in ▁length ▁at ▁ground ▁level ▁and ▁extends ▁down wards ▁into ▁the ▁ground ▁up ▁to ▁several ▁meters . ▁During ▁the ▁winter ▁months , ▁the ▁water ▁in ▁the ▁ground ▁free zes ▁and ▁exp ands . ▁Once ▁temper atures ▁reach ▁− 1 7 ▁degrees ▁Cel si us ▁or ▁lower , ▁the ▁ice ▁that ▁has ▁already ▁formed ▁acts ▁like ▁a ▁solid ▁and ▁exp ands ▁to ▁form ▁cra cks ▁in ▁the ▁surface ▁known ▁as ▁ice ▁wed ges . ▁As ▁this ▁process ▁continues ▁over ▁many ▁years ▁ice ▁wed ges ▁can ▁grow , ▁up ▁to ▁the ▁size ▁of ▁a ▁sw imming ▁pool . ▁Ice ▁wed ges ▁usually ▁appear ▁in ▁a ▁pol yg onal ▁pattern ▁known ▁as ▁ice ▁w edge ▁pol yg ons . ▁The ▁cra cks ▁can ▁also ▁be ▁filled ▁with ▁materials ▁other ▁than ▁ice , ▁especially ▁sand , ▁and ▁then ▁they ' re ▁called ▁sand ▁wed ges . ▁ ▁Form ation ▁There ▁are ▁many ▁theories ▁that ▁attempt ▁to ▁explain ▁the ▁origin ▁of ▁ice ▁wed ges ▁but ▁only ▁one ▁has ▁been ▁consist ently ▁supported ▁by ▁most ▁prominent ▁scient ists : ▁the ▁thermal ▁contra ction ▁theory . ▁