Complex sentence: The Salento peninsula is in fact a whole rock of limestone dividing the Adriatic and Ionic seas and the countryside around Grottaglie is scattered with vast and deep ravines that open the ground into the heart of the limestone-rock.
Split into simpler sentences: The Salento peninsula is in fact a whole rock of limestone dividing Adriatic sea from Ionic sea. The countryside around Grottaglie is scattered with vast and deep ravines that open the ground into the heart of the limestone-rock.