Making a Timeline

The following table shows significant evolutionary/geological events, when they happened,
and where they would be placed on a time line 15 meters long.

Time (Myr ago)	Event	distance from present 1 meter = 1 billion years
12-15 billion yrs	Big Bang	12-15 meters
4600	Formation of the approximately homogeneous solid Earth by planetesimal accretion	4.6 meters
4300	Melting of the Earth due to radioactive and gravitational heating which leads to its differentiated interior structure as well as outgassing of molecules such as water, methane, ammonia, hydrogen, nitrogen, and carbon dioxide	4.3 meters
4300	Atmospheric water is photodissociated by ultraviolet light to give oxygen atoms which are incorporated into an ozone layer and hydrogen molecules which escape into space	4.3 meters
4000	Bombardment of the Earth by planetesimals stops	4.3 meters
3800	The Earth's crust solidifies---formation of the oldest rocks found on Earth Condensation of atmospheric water into oceans	3.8 meters
3500--2800	Prokaryotic cell organisms develop Beginning of photosynthesis by blue-green algae which releases oxygen molecules into the atmosphere and steadily works to strengthen the ozone layer and change the Earth's chemically reducing atmosphere into a chemically oxidizing one	3.5-2.8 meters
1500	Eukaryotic cell organisms develop	1.5 meters
1500--600	Rise of multicellular organisms	1.5-.6 meters
580--545	Fossils of Ediacaran organisms are made	54-58 cm.
545	Cambrian explosion of hard-bodied organisms	54.5 cm.
500--450	Rise of the fish---first vertebrates	45-50 cm.
430	Waxy coated algae begin to live on land	43 cm.
420	Millipedes have evolved---first land animals	42 cm.
375	Appearance of primitive sharks	37.5 cm.
350--300	Rise of the amphibians	30-35 cm.
350	Primitive insects have evolved	35 cm.
350	Primitive ferns evolve---first plants with roots	35 cm.
300--200	Rise of the reptiles	20-30 cm.
300	Winged insects have evolved	30 cm.
280	Beetles and weevils have evolved	28 cm
250	Permian period mass extinction	25 cm.
230	Roaches and termites have evolved	23 cm.
225	Modern ferns have evolved	22.5 cm.
225	Bees have evolved	22.5 cm.
200	Pangaea starts to break apart	20 cm.
200	Primitive crocodiles have evolved	20 cm.
200	Appearance of mammals	20 cm.
145	Archaeopteryx walks the Earth	14.5 cm.
136	Primitive kangaroos have evolved	13.6 cm.
90	Modern sharks have evolved	9 cm.
65	The Chicxulub impact occurs	6.5 cm
65	K-T Boundary---extinction of the dinosaurs and beginning of the reign of mammals 60 Rats, mice, and squirrels have evolved	6.5 cm
60	Herons and storks have evolved	6 cm.
55	Rabbits and hares have evolved	5.5 cm
50	Primitive monkeys have evolved	5 cm
28	Koalas have evolved	2.8 cm
20	Parrots and pigeons have evolved	2 cm.
20--12	The chimpanzee and hominid lines evolve	1.2-2.0 cm.
4	Development of hominid bipedalism	4 mm
4--1	Australopithecus exist	1-4 mm
3.5	The Australopithecus Lucy walks the Earth	3.5 mm
2	Widespread use of stone tools	2 mm
2	Most recent ice age	2 mm
1.6	Homo erectus exist	1.6 mm
0.05--0	Homo sapiens sapiens exist	.05 mm
	To the Future
+4500	Sun's nuclear fusion ends (in 4.5 billion years)	+4.5 meters

If the time from the big bang to the present is reprsented by a 15 meter line, all of human existance is in the last 20th of a millimeter.

5000--1500 Archeozoic (Archean) era
1500--545 Proterozoic era Paleozoic era ``Ancient life''
545--505 Cambrian period
505--438 Ordovician period
438--410 Silurian period
410--355 Devonian period
355--290 Carboniferous (Mississippian/Pennsylvanian) period
290--250 Permian period Mesozoic era ``Middle Life''
250--205 Triassic period
205--135 Jurassic period
135--65 Cretaceous period Cenozoic era ``Recent Life'' Tertiary (Paleogene/Neocene) period
65--55 Paleocene epoch
55--38 Eocene epoch
38--26 Oligocene epoch
26--6 Miocene epoch
6--1.8 Pliocene epoch Quaternary period
1.8--0.01 Pleistocene epoch
0.50--0.25 Lower Paleolithic0.25--0.06 Middle Paleolithic
0.06--0.01 Upper Paleolithic
0.01--0 Holocene epoch