Complex sentence: Further along the coast, going towards Clifton, there is a plaque overlooking the rocks what commemorates Charles Darwin's observation of a unique junction where igneous rock has invaded and replaced metamorphic rock.
Split into simpler sentences: Further along the coast, going towards Clifton, there is a plaque overlooking the rocks. This commemorates Charles Darwin's observation of a rare geological interface, where igneous rock has invaded, absorbed and replaced metamorphic rock.