The earth's continents move with <em>time</em>. Over thousands and thousands of years, areas that were at sea level (or below sea level) that contain <em>fossils of animals, plants</em> and other deposits move with the surface and may end up in mountain ranges, which are the result of two continents pushing against each other.
All of the fossils could be from fish,dinosoures,leaves, or plants. The reason why this could happen is because it could have happened thousand of years ago and the sea level could have been lower.
“A picture!” said the old gentleman with the haunted head. “A picture!” cried the narrator with the waggish nose. “A picture! a picture!” echoed several voices.