▁acc ret ed ▁to ▁the ▁side ▁of ▁the ▁block . ▁In ▁the ▁early ▁Pale oz o ic ▁the ▁Q a id am ▁was ▁acc ret ed ▁to ▁the ▁south ▁and ▁in ▁the ▁late ▁Pale oz o ic ▁the ▁Y ili ▁Ter rane ▁was ▁acc ret ed ▁to ▁the ▁north ▁of ▁the ▁block . ▁Ig ne ous ▁activity ▁finished ▁in ▁the ▁block , ▁after ▁the ▁formation ▁of ▁a ▁large ▁ igne ous ▁province ▁in ▁the ▁Perm ian . ▁ ▁H imal ay an ▁O ro gen ▁▁ ▁The ▁T eth ys ▁Ocean ▁closed ▁about ▁ 5 0 ▁million ▁years ▁ago ▁and ▁Ind o - Austral ian ▁Pl ate ▁began ▁to ▁col lide ▁with ▁Asia . ▁The ▁H imal aya ▁is ▁now ▁mostly ▁formed ▁from ▁the ▁u pl ift ed ▁sed iment ary ▁rocks ▁from ▁this ▁ocean . ▁These ▁sed iment ary ▁rocks ▁along ▁with ▁associated ▁ igne ous ▁rocks , ▁now ▁often ▁met am orph osed , ▁from ▁a ▁series ▁of ▁East - West ▁sli vers ▁of ▁rock ▁through ▁the ▁mountain ▁range . ▁From ▁South ▁to ▁North ▁there ▁are ▁four ▁main ▁t ect onic ▁sub - un its ▁within ▁the ▁H imal aya : ▁the ▁sub - H imal aya , ▁L esser ▁H imal aya , ▁Central ▁H imal ay an ▁Domain ▁and ▁Ind us ▁S uture ▁Zone . ▁ ▁The ▁H imal aya ' s ▁fo oth ills ▁or ▁sub - H imal aya ▁are ▁Mi oc ene ▁to ▁Ple ist oc ene ▁sed iments ▁that ▁have ▁er oded ▁off ▁the ▁mountain