▁di ary ▁recording ▁their ▁finds , ▁which ▁included ▁a ▁sea ▁mouse ▁and ▁a ▁c utt le fish . ▁In ▁his ▁second ▁year ▁Charles ▁became ▁active ▁in ▁student ▁soci eties ▁for ▁natural ists , ▁and ▁joined ▁with ▁others ▁interested ▁in ▁collect ing ▁on ▁the ▁sh ores ▁of ▁the ▁F irth . ▁ ▁References ▁ ▁External ▁links ▁ ▁The ▁Natural ist ' s ▁P ocket ▁Book ▁online ▁ ▁Works ▁by ▁George ▁Gra ves ▁at ▁B iod iversity ▁Heritage ▁Library ▁ ▁Category : 1 7 8 4 ▁birth s ▁Category : 1 8 3 9 ▁death s ▁Category : Al umn i ▁of ▁the ▁University ▁of ▁Edinburgh <0x0A> </s> ▁The ▁Ta iga ▁Sh ield ▁E co zone , ▁as ▁defined ▁by ▁the ▁Commission ▁for ▁Environment al ▁Co operation ▁( CE C ), ▁is ▁an ▁e co zone ▁which ▁st ret ches ▁across ▁Canada ' s ▁sub ar ctic ▁region . ▁Some ▁regions ▁exhib it ▁exposed ▁P rec amb rian ▁bed rock ▁of ▁the ▁Canadian ▁Sh ield , ▁the ▁oldest ▁of ▁the ▁world ' s ▁ge ological ▁form ations . ▁The ▁world ' s ▁oldest ▁rocks , ▁d ating ▁to ▁four ▁billion ▁years , ▁are ▁found ▁in ▁the ▁Canadian ▁Sh ield ▁north ▁of ▁Great ▁S lave ▁Lake . ▁ ▁Geography ▁The ▁Ta iga ▁Sh ield ▁e co zone ▁covers ▁almost ▁all ▁of ▁the ▁eastern ▁area ▁of ▁the ▁North west ▁Territ ories , ▁a ▁tiny ▁corner ▁of ▁n ort he astern ▁Al berta , ▁a ▁narrow ▁strip ▁of ▁all ▁northern ▁S ask atch ew an ▁and ▁north western