The 2011 GNS claims of rediscovery were challenged by Bill Keir, who calculated that the 'rediscovered' structures were not where the terraces had been before the eruption. Specifically, the then newly discovered structures were under the lake surface, but the historic terraces were expected to be as little as under, and "could not be more than below the surface". Keir speculated that the structures discovered by the GNS team were prehistoric terraces, never before seen by humans; or perhaps step-shaped objects created by the eruption.</ref>