About 4 to 3.8 billion years ago a period of intense comet and
asteroid bombardment is thought to have peppered all the planets
including the Earth.
Geological Time Scale
used by geologists and other scientists to map the timing and
relationships between events that have occurred during the history of
the Earth.
Layers of the Earth
The Earth consists of four concentric layers: inner core, outer core, mantle and
crust. The crust is made up of tectonic plates, which are in constant motion.
Stratigraphy
branch of geology concerned with the order and relative position of strata and
their relationship to the geological time scale.
Fossil Records
Fossil record, history of life as documented by fossils, the remains or
imprints of previous living ,from earlier geological periods preserved in
sedimentary rock.
Relative Dating
Relative dating is the science of
determining the relative order of past
events ,meaning how old the layers of rock
are.Typically, the oldest rocks are all the
way in the bottom.
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology. Some
scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted
certainty of accuracy.