etic ▁ice ▁w edge , ▁the ▁age ▁of ▁the ▁ice ▁on ▁the ▁peri ph ery ▁changes ▁little ▁from ▁top ▁to ▁bottom . ▁ ▁Sy ng en etic ▁Sy ng en etic ▁ice ▁wed ges , ▁like ▁the ▁ep igen etic ▁variety , ▁find ▁their ▁roots ▁in ▁the ▁ge ological ▁term ▁sy ng en etic , ▁which ▁means ▁forming ▁at ▁the ▁same ▁time ▁as ▁the ▁surrounding ▁material . ▁This ▁is ▁because ▁sy ng en etic ▁ice ▁wed ges ▁grow ▁as ▁the ▁upper ▁per ma f rost ▁surface ▁r ises ▁in ▁response ▁to ▁the ▁addition ▁of ▁material ▁on ▁the ▁ground ▁surface . ▁This ▁allows ▁sy ng en etic ▁ice ▁wed ges ▁to ▁grow ▁very ▁deep , ▁as ▁the ▁surface ▁around ▁them ▁r ises ▁with ▁the ▁accum ulation ▁of ▁all u vi um ▁( in ▁flo od pla ins ), ▁pe at ▁( in ▁t und ra ), ▁and ▁gel if lu ction ▁depos its ▁( at ▁the ▁bottom ▁of ▁a ▁slope ), ▁among ▁other ▁materials . ▁Sy ng en etic ▁ice ▁wed ges ▁may ▁only ▁form ▁if ▁the ▁thermal ▁contra ction ▁and ▁subsequent ▁ice - ve in let ▁growth ▁can ▁keep ▁pace ▁with ▁the ▁addition ▁of ▁new ▁material . ▁If ▁this ▁is ▁the ▁case , ▁the ▁ice ▁w edge ▁can ▁reach ▁depth s ▁of ▁ 2 5 ▁meters , ▁but ▁the ▁average ▁is ▁much ▁less . ▁In ▁a ▁sy ng en etic ▁ice ▁w edge , ▁the ▁age ▁of ▁the ▁ice ▁on ▁the ▁peri ph ery ▁decre ases ▁up wards . ▁ ▁Anti - S