Long barrows have been confused with coniger mounds and rabbit warrens, sometimes termed pillow mounds, which can take on a similar shape.[53] Rifle butts can also sometimes take on shapes similar to those of long barrows.[54] Later landscaping has also led to misidentification; the two mounds at Stoke Park in Bristol, southwest England were for instance thought to be long barrows until an excavation in the 1950s revealed that they post-dated the Middle Ages, and thus must have been created by more recent landscaping projects.[54] In areas which were previously impacted by glaciation, moraine deposits on valley floors have sometimes been mistaken for long barrows.