Wikipedia se
Photo of the OrdovicianSilurian boundary, an example of marine transgression as exposed on the Southern tip of the Hovedøya island, Norway. Due to the folding of the Caledonian mountain range, the layers have been inverted, leaving Ordovician granular limestone on top of the later Silurian brownish mudstone.

Bhuvigyan (Geology) dunia jon sab nonliving chij se banaa hae ke baare me parrhae hae.