Mt Washington is a 6288 feet high peak in the white mountains of New Hampshire and also known as the "home of the world's worst weather". If you look at the topographical map of the region, you notice that the rivers and brooks always cross the level curves perpendicularly. Water goes in the direction of the steepest decent. But there is an anomaly. If you follow from the Nelson Crag the Nelson Crag Trail, you follow the springs of a couple of brooks. Two of them do not follow the same pattern and cross the level curves in an angle which is not 90 degrees. Can you find the reason? (The reason is not mathematical. And it is not the fact that winds on Mt Washington can reach 231 miles per hour.)

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