I wondered about countries too. Currently I'm in Switzerland which is a long way from the sea compared to Norway which hs a very high ridge running down it's spine - as does much of Scotland. So my theory now tends towards specific geographics - the further from the the sea that a river can originate may have bearing on the average fall/km of that water. The lessor the rate of climb and the further away from the sea could indicate a longer but easier route for returning hens?
This is all pretty far away of the things I should be concentrating on at present. Body position, leg flex, carving turns, skating turns and falling over turns!