A sedimentary rock containing a fern fossil tells that the area was on land at the time the rock was formed.
Explanation:
Ferns are vascular plants that thrive on land. They are mostly found in moist, shades and mountainous area in the country. If a ferns fossil are found under a sedimentary rock, this only means that previously the area is a land and was not submerged under water. Geological process that takes place over a period of time may have contributed to the change in the location and topography of the area.