Dave’s Geologic Time Scale

Era	Period	Epoch	Biological Features	Geological Features	Alaskan Features	MYA
Precambrian	Azoic		No Life	Earth becomes a single mass.		4600+
	Archaeozoic		Blue Green Algae,Bacteria	1st permanent crust solidifies.		4000
	Proterozoic		Multicellular Organisms	Pannotia Supercontinent forms. 1st major glaciation occurs.	Oldest rocks in Alaska form 2.2 bya in the Kilbuck Terrane. Arctic and Yukon Composite Terranes form in the vicinity of northeast North America.	2500
Paleozoic	Cambrian		Shellfish, Mollusks	Pannotia breaks up into Gondwanaland, Baltica, Siberia and Laurentia.	Alexander Terrane forms in an equatorial ocean	570
	Ordovician		Vertebrates,Fish, Freshwater Plants	Taconic Mountains form as an island arc collides with Laurentia.		505
	Silurian		Land Plants, Insects	Caledonian Mountains form when Baltica collides with Laurentia.		440
	Devonian		Trees, Amphibians	Caledonian Mountains uplifted further when Gondwanaland collides with Laurentia.	Yukon Terrane part of North America by this time.	408
	Mississipian		Sharks, Winged Insects	Tropical location creates widespread limestone formation on Laurentia. Laurentia and Gondwanaland separate.	Yukon Composite Terrane rifts apart from North America.	360
	Pennsylvanian		Coniferous Trees, Reptiles	Warm, wet climate on Laurentia creates massive coal swamps. Gondwanaland/Laurentia collision creates the Appalacian Mountains.		320
	Permian		Mass Marine Extinctions	Ural Mountains created when Siberia collides with Baltica. Pangaea Supercontinent forms.	Ruby Terrane and Central Composite Terrane approach North America from the northwest.	286
Mesozoic	Triassic		Dinosaurs, Mammals	Pangaea breaks up.	Wrangellia Terrane forms as Alexander Terrane rifts apart, forming the Wrangellia Composite Terrane. Peninsular Terrane joins the Wrangellia Composite Terrane.  Chugach Terrane begins to form. Kahiltna Terrane begins to form.	245
	Jurassic		Birds	Africa and South America separate from North America and Europe.	Yukon Composite Terrane collides back into North America.  Arctic CT rifts apart from Canada and rotates towards present location.	208
	Cretaceous		Flowers, Dinosaurs extinct at end of Cretaceous.	Modern southern continents begin to form as Gondwanaland splits apart. Uplift of Rocky Mountains begins when North America begins to move westward..	Wrangellia CT collides with North America in eastern Oregon and begins to slide northward.	144
Cenozoic	Tertiary	Paleocene	Ancestral Horses, Elephants and Bears	Continued uplift of Rockies.	Prince William Terrane begins to form.	65
		Eocene	Grasses, Grazing Mammals, Marine Mammals enter the sea	Rockies completed.	Yakutat Terrane begins to form. Aleutian Trench forms. Kula-Pacific plate movement changesf from north to northwest. Alaska Range begins to be uplifted by collision with Wrangellia.	58
		Oligocene	Apes, Large Mammals	Japan splits from Asia. North America separates from Europe. Africa collides with Europe to create the Alps.	Wrangell Mountains begin to form through volcanism.	37
		Miocene	Great Apes and Hominid Apes diverge.	Cascade Mountains form. Himalayas form as India collides with Asia. East African Rift appears.	Chugach and St. Elias Mountains begin to uplift.	24
		Pliocene	1st true Hominids	Antarctica separates from South America. Kauai  forms.		5
	Quaternary	Pleistocene	Modern Humans	Major glaciation occurs. Hawaii forms.	Glaciers usually cover most of Alaska. Cook Inlet volcanoes begin to form.	1.6
		Holocene	Life as we know it	Glacial retreat. Rising sea levels.	Glacial retreat. Rising sea levels.	.01

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