Geologic time is a very difficult concept for humans to grasp
because of it's sheer magnitude. A million years is a very, very
long time in human terms. The Earth was formed 4,500 million
years ago. One thousand five hundred million years later, 3000
million years ago, the first life form, cyanobacteria appeared.
Very early complex life forms first began to flourish 550 million
years ago at the beginning of the Cambrian Period.
One million years ago, man first began to fashion VERY crude
pebble tools. What will earth be like a million years from now?
Please click another colored block to learn more about Earth's
Please note that, except for the precambrian era, the time
line is to scale. Notice also that the Quaternary Period (2mya
to recent), which included the Holocene Epoch which began 100,000
years ago, is so small it doesn't fit on the chart. Please click
Cenozoic Time for a zoom.
for a list of references