John I.K., that essay's not talking about a herd, it's saying that the entire island is made of the skeletal remains of many ancient herds (mammoths, hippos and rhinocerous) and that the bones are not laying in neat order where anyone could sort them out, but spread jumbled and mixed with the remains of uprooted trees. Since there was no food source in the Arctic circle at that time, that could support such an enormous number of herbivores, I think they are suggesting that the land itself somehow shifted there from a more temporate clime at a high rate of speed carrying and shredding the animals as it slid, skidded or rolled to it's present location. Maybe the whole story is false and some sort of mid 19th century investment scheme but it would be something if such a place was really there.