▁the ▁Rot lie g endes ▁with ▁contin ental ▁depos itions . ▁Later , ▁during ▁the ▁Ze ch stein ▁and ▁Mus ch el k alk ▁the ▁region ▁was ▁largely ▁flo oded ▁by ▁the ▁sea . ▁B unter ▁sand stone ▁and ▁Ke uper ▁are ▁again ▁largely ▁of ▁contin ental ▁origin . ▁But ▁even ▁in ▁these ▁rocks ▁the ▁per imeter ▁regions ▁have ▁marine ▁influ ences , ▁short ▁inc urs ions ▁of ▁the ▁sea ▁also ▁reached ▁the ▁centre ▁of ▁the ▁bas in ▁in ▁northern ▁Germany . ▁ ▁During ▁the ▁Ze ch stein ▁the ▁sea ▁ing ress ed ▁from ▁the ▁Ar ctic ▁Ocean ▁to ▁the ▁north ▁into ▁the ▁bas in . ▁This ▁gateway ▁closed ▁during ▁the ▁U pp erm ost ▁Perm ian . ▁In ▁the ▁Tri ass ic ▁these ▁marine ▁inc urs ions ▁came ▁through ▁several ▁" port als " ▁in ▁the ▁south ▁of ▁the ▁bas in ▁e . g . ▁the ▁East ▁Car path ian ▁Gate ▁( E ast ▁Poland ), ▁the ▁S iles ian ▁Gate ▁( West ▁Poland ) ▁and ▁the ▁Burg und ian ▁Gate ▁( France ). ▁During ▁the ▁R ha et ian ▁stage , ▁new ▁in lets ▁formed ▁in ▁the ▁north west ▁of ▁the ▁bas in ▁through ▁the ▁former ▁high lands ▁in ▁Ireland ▁and ▁Scotland , ▁which ▁came ▁from ▁the ▁Atlantic ▁Ocean ▁which ▁was ▁now ▁opening ▁up . ▁ ▁Liter ature ▁ ▁Ger hard ▁Be ut ler ▁und ▁Jo achim ▁Sz ul c : ▁Die ▁pal ä oge ograph ische ▁Entwicklung ▁des ▁German ischen ▁Beck ens ▁in ▁der ▁Tri as ▁und ▁die ▁Ver bindung