res ▁with ▁its ▁over t ▁sense ▁of ▁cre ative ▁det achment , ▁classical ▁music ▁pret ensions , ▁and ▁experimental , ▁avant - gar de ▁pro cl iv ities . ▁ ▁In ▁the ▁rock ▁music ▁of ▁the ▁ 1 9 7 0 s , ▁the ▁" art " ▁des criptor ▁was ▁generally ▁understood ▁to ▁mean ▁" ag gress ively ▁avant - gar de " ▁or ▁" pret ent iously ▁progress ive ". ▁" Art ▁rock " ▁is ▁often ▁used ▁syn onym ously ▁with ▁progress ive ▁rock . ▁Histor ically , ▁the ▁term ▁has ▁been ▁used ▁to ▁describe ▁at ▁least ▁two ▁related , ▁but ▁distinct , ▁types ▁of ▁rock ▁music . ▁The ▁first ▁is ▁progress ive ▁rock , ▁while ▁the ▁second ▁usage ▁refers ▁to ▁groups ▁who ▁rejected ▁psych ed elia ▁and ▁the ▁hi pp ie ▁counter c ulture ▁in ▁favor ▁of ▁a ▁modern ist , ▁avant - gar de ▁approach ▁defined ▁by ▁the ▁Vel vet ▁Under ground . ▁Ess ay ist ▁Ellen ▁Will is ▁compared ▁these ▁two ▁types : ▁ ▁Art ▁rock ▁emphas izes ▁Rom antic ▁and ▁autonom ous ▁trad itions , ▁in ▁distinction ▁to ▁the ▁a est h etic ▁of ▁the ▁every day ▁and ▁the ▁dispos able ▁emb od ied ▁by ▁art ▁pop . ▁Larry ▁St arr ▁and ▁Christopher ▁Wat erman ' s ▁American ▁Popular ▁Music ▁defines ▁art ▁rock ▁as ▁a ▁" form ▁of ▁rock ▁music ▁that ▁bl ended ▁elements ▁of ▁rock ▁and ▁European ▁classical ▁music ", ▁cit ing ▁the ▁English ▁rock ▁bands ▁King ▁C rim son , ▁Em erson , ▁Lake ▁& ▁Pal