▁boundary . ▁Struct ural ▁ge olog ists ▁divide ▁it ▁into ▁the ▁und e formed ▁sed iment ary ▁and ▁vol can ic ▁rocks ▁K ania pis k au ▁Super group ▁in ▁the ▁Lab r ador ▁Tr ough ▁( including ▁gab bro ▁s ills ▁and ▁plut ons ) ▁in ▁the ▁west ▁and ▁high - grade ▁an orth os ite ▁and ▁g ne iss ▁in ▁the ▁east . ▁ ▁V irt ually ▁all ▁of ▁southern ▁Lab r ador ▁belongs ▁to ▁the ▁major ▁Gren ville ▁Province , ▁which ▁under lies ▁much ▁of ▁eastern ▁Canada ▁and ▁the ▁northern ▁US . ▁Ext ensive ▁fault ing ▁and ▁my lon ite ▁marks ▁its ▁northern ▁boundary ▁with ▁the ▁other ▁struct ural ▁provinces . ▁Ar che an ▁g ne isses ▁were ▁met am orph osed ▁again ▁during ▁the ▁Gren ville ▁or ogen y ▁and ▁intr ud ed ▁by ▁an orth os ite - ad am ellite ▁plut ons . ▁The ▁K ania pis k au ▁Super group ▁extends ▁into ▁the ▁Gren ville ▁Province , ▁marked ▁by ▁mar ble ▁and ▁quart z ite . ▁▁ ▁During ▁the ▁Pale oz o ic ▁around ▁ 3 3 4 ▁million ▁years ▁ago , ▁flo od ▁bas al ts ▁emp la ced ▁in ▁northern ▁New found land ▁and ▁southern ▁Lab r ador . ▁ ▁Through ▁the ▁Mes oz o ic ▁and ▁into ▁the ▁C en oz o ic , ▁the ▁landscape ▁er oded , ▁shed ding ▁sand ▁into ▁the ▁Lab r ador ▁Sh elf , ▁mainly ▁from ▁older ▁met ased iments ▁and ▁met av ol can ic ▁rocks