A tree has fallen across the noisy creek and is covered with snow. Each person who comes to the narrow bridge that crosses the creek nearly slips over. Then they stop to look at the fallen tree.

'The map's wrong,' shouts Amy. She's been standing in the middle of the bridge unfolding and refolding her Mountain Park map. Every one who has squeezed passed has bumped into her and said, 'Sorry.' Except Farrel.

Amy shouts at their retreating backs, 'This creek must start much higher up and we won't have time to find its source today.'

'Woah, Neddy,' say Penny Marx and Tommy Tompson together--and laugh. 'What do you think, every one,' says Penny, 'will we find the true source of the rivulet another time, maybe? When there's no snow? A family project for someone?'