▁by ▁thick ▁h ed ger ows , ▁has ▁almost ▁disappeared ▁since ▁the ▁ 1 9 6 0 s ▁to ▁fit ▁the ▁modern ▁agricult ural ▁needs ▁and ▁methods , ▁particularly ▁mechan isation . ▁ ▁Several ▁for ests ▁still ▁exist , ▁such ▁as ▁the ▁Pa imp ont ▁forest , ▁sometimes ▁said ▁to ▁be ▁the ▁Arthur ian ▁Bro c éli ande . ▁The ▁poor ▁and ▁rock y ▁areas ▁are ▁covered ▁by ▁large ▁he ath land ▁and ▁mo or lands , ▁and ▁Brit t any ▁has ▁several ▁mar sh es , ▁like ▁the ▁B rière , ▁included ▁in ▁a ▁regional ▁natural ▁park . ▁Another ▁regional ▁park ▁en comp ass es ▁the ▁Mont s ▁d ' Arr ée ▁and ▁the ▁I ro ise ▁se aco ast . ▁The ▁I ro ise ▁Sea ▁is ▁also ▁a ▁UN ES CO ▁b ios phere ▁reserve . ▁ ▁Ge ology ▁ ▁The ▁Bre ton ▁pen ins ula ▁appeared ▁during ▁the ▁Cad om ian ▁O ro gen y , ▁which ▁formed ▁its ▁northern ▁coast line , ▁between ▁Gu ing amp ▁and ▁F oug ères . ▁The ▁southern ▁part ▁emer ged ▁during ▁the ▁Her c yn ian ▁or ogen y . ▁At ▁the ▁same ▁time , ▁an ▁inten se ▁vol can ic ▁activity ▁left ▁large ▁quantities ▁of ▁gran ite . ▁Between ▁the ▁Cad om ian ▁and ▁Her c yn ian ▁periods , ▁the ▁region ▁was ▁sub mer ged ▁several ▁times ▁and ▁the ▁sea ▁left ▁foss ils ▁and ▁sed iment ary ▁rocks , ▁mostly ▁sch ist ▁and ▁sand stone . ▁Because ▁of ▁the ▁absence ▁of