Complex sentence: Land-ice never reached Strandzha during the ice-ages of the Pleistocene and the Holocene and this lack of glaciations has helped create the circumstances in which flora characteristic for the Tertiary period on the European continent has been preserved in Strandzha.
Split into simpler sentences: Land-ice never reached Strandzha during the ice-ages of the Pleistocene and the Holocene. This lack of glaciations helped create the circumstances in which flora characteristic for the Tertiary period on the European continent has been preserved in Strandzha.