<Tr> <Td> Greenland </Td> <Td> 251 km (97 sq mi) </Td> </Tr> <Tr> <Td> Ural Mountains </Td> <Td> 125 km (48 sq mi) </Td> </Tr> <Tr> <Td> Andes </Td> <Td> 100 km (39 sq mi) </Td> </Tr> <Tr> <Td> Rocky Mountains (US and Canada) </Td> <Td> 100 km (39 sq mi) </Td> </Tr>

Layer of unfrozen ground above below or within perma frost