▁of ▁the ▁ocean ic ▁and ▁contin ental ▁l ith os phere ▁called ▁ter ran es ▁created ▁the ▁North ▁C asc ades ▁about ▁ 5 0 ▁million ▁years ▁ago . ▁ ▁During ▁the ▁Ple ist oc ene ▁period ▁d ating ▁back ▁over ▁two ▁million ▁years ▁ago , ▁gla ci ation ▁adv ancing ▁and ▁retre ating ▁repeatedly ▁sc oured ▁the ▁landscape ▁leaving ▁depos its ▁of ▁rock ▁de br is . ▁The ▁“ U ” - sh aped ▁cross ▁section ▁of ▁the ▁river ▁valle ys ▁are ▁a ▁result ▁of ▁recent ▁gla ci ation . ▁U pl ift ▁and ▁fault ing ▁in ▁combination ▁with ▁gla ci ation ▁have ▁been ▁the ▁dominant ▁processes ▁which ▁have ▁created ▁the ▁tall ▁pe aks ▁and ▁deep ▁valle ys ▁of ▁the ▁North ▁C asc ades ▁area . ▁ ▁See ▁also ▁▁ ▁Geography ▁of ▁Washington ▁( state ) ▁ ▁Ge ology ▁of ▁the ▁Pacific ▁North west ▁ ▁List ▁of ▁High est ▁Mountain ▁Pe aks ▁in ▁Washington ▁ ▁References ▁ ▁Gallery ▁ ▁External ▁links ▁ ▁Ruby ▁Mountain ▁weather : ▁Mountain ▁Fore cast ▁ ▁Category : Mount ains ▁of ▁Washington ▁( state ) ▁Category : Mount ains ▁of ▁What com ▁County , ▁Washington ▁Category : N orth ▁C asc ades ▁Category : C as cade ▁Range <0x0A> </s> ▁Qu am ▁Lake ▁is ▁a ▁lake ▁in ▁Douglas ▁County , ▁in ▁the ▁U . S . ▁state ▁of ▁Minnesota . ▁ ▁Qu am ▁Lake ▁was ▁named ▁for ▁P . ▁J . ▁Qu am . ▁ ▁See ▁also ▁List ▁of ▁la kes ▁in ▁Minnesota ▁ ▁References ▁ ▁Category :