A remarkable dropstone from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, southern England

• Published in: Proceedings of the Geologists' Association 2020-08, Vol.131 (3-4), p.301-308
• Main Authors: Sweetman, Steven C., Goodyear, Matthew
• Format: Article
• Language: English
• Subjects: Dropstone; Early Cretaceous; Gastrolith; Hornfels; Wealden; Wessex Formation
• ISSN: 0016-7878
• DOI: 10.1016/j.pgeola.2019.06.005

A remarkably large, derived, metamorphic clast of Palaeozoic aspect weighing approximately 20 kg was recently recovered from a plant debris bed occurring in the Lower Cretaceous (Barremian), fluvial, lacustrine and terrestrial Wessex Formation exposed on the south-west coast of the Isle of Wight, southern England. It is interpreted as a dropstone transported in tree roots from a source locality on the Cornubian Massif. During the Early Cretaceous the eastern extremity of this has been estimated to be some 110 km to the west of the collection locality. Polished extrabasinal clasts of similar lithology are commonly encountered in the Wessex Formation but all recorded to date are much smaller and the majority have been interpreted as gastroliths, although some must be dropstones. The occurrence of this clast demonstrates long distance, floating transport of large root systems and therefore the potential to transport, over long distances, some of the logs and dinosaur remains encountered in the Wessex Formation. Direct evidence for this has been lacking until now and it suggests that some of the dinosaurs recorded from the Wessex Formation of the Isle of Wight may not have been floodplain residents or visitors.