|
Geologists use clues from earthquakes and volcanoes
to explore how the Earth’s lithosphere is moving today. However, clues
from fossils, paleomagnetism, and rocks can help reconstruct how the
Earth’s surface looked in the past.
When the Earth first formed 4.5 billion years ago,
there was probably no water. So the land masses included the entire
crust of the Earth. Evidence of an atmosphere and basins of water did
not reveal itself until 3.5 billion years ago. Determining what the
surface of the land looked like back then is almost impossible.
The continents are embedded into the plates. The
rocks that compose the continents are less dense than the rocks that
make up the ocean basin. The majority of continental crust seems to
remain on the top of the lithosphere. The continental rocks provide
clues of how the Earth formed over the last 3.5 billion years (the
oldest rocks found on continents). The older the rock the unclearer the
clues are. It is like an ancient murder mystery, the clues are long gone
to the investigator.
|
Today
|
