sentences:  The long trains of carts drawn by oxen were replaced by railway trains powered by steam, and the trails reverted to nature.A few traces of the vanished trails still exist.Some local roads follow their routes; depressions in the landscape show where thousands of carts once passed, and even after more than a century of winters and springs, freezing and thawing the land, there are still places where soils remain compacted and resistant to the plow.