Final answer:
The presence of seashell fossils on mountaintops indicates that these areas were once submerged underwater, and the Earth's tectonic activity has raised them to form mountains.
Step-by-step explanation:
The presence of seashell molds and casts on mountaintops informs us about the Earth's geological history. Specifically, it tells us that the area was once underwater. These fossils are evidence of ancient sea life that settled on the ocean floor, later becoming buried by layers of sediment.
Over geological timescales, tectonic forces lifted these sediments, forming mountains and bringing the seashell fossils to the surface, away from the ancient oceans they once inhabited. Additionally, the idea of rock layers representing the chronological order of events allows us to trace the history of Earth and life on our planet.
These rocks were then uplifted to form mountains through geological processes like tectonic movements.This evidence supports the idea that the Earth's surface has undergone significant changes over time, including the presence of oceans where mountains now stand.