Earth History Timeline

Era	Period	Million Years before present	Events
Cenozoic	Quaternary	1.6	Most recent period of Ice Ages begins 80,000 years ago. Last Ice sheets retreat around 14,000 years ago. Map of the Earth 18,000 years ago (at the point of maximum glacier coverage)
Cenozoic	Tertiary	65	Map of the Earth ~14 million years ago Map of the Earth ~50 million years ago
Mesozoic	Cretaceous	145	Map of the Earth ~66 million years ago (Late Cretaceous - just before the mass extinction in which dinosaurs became extinct) Map of the Earth ~94 million years ago (Late Cretaceous)
	Jurassic	208	Medford Gabbro forms - 190 million years ago Pangaea begins to break apart. Atlantic Ocean begins to open. Map of the Earth ~152 million years ago (Late Jurassic) Map of the Earth ~195 million years ago (Early Jurassic)
	Triassic	245	Map of the Earth ~237 million years ago (Early Triassic)
Paleozoic	Permian	286	Pangaea assembled. Mass Extinction where well over 90% of all life became extinct! Map of the Eearth ~255 million years ago (Late Permian)
	Carboniferous	360	Weathering and erosion of mountains form Pondville Conglomerate Map of the Earth ~306 milion years ago (Late Carboniferous) Map of the Earth ~356 million years ago (Early Carboniferous)
	Devonian	417	Nashoba and Avalon collide with Laurentia - "Acadian Mountain building event". Bloody Bluff Fault Zone is created between Nashoba and Avalon Rifts in Avalon continue, continuing formation of granites. Map of the Earth ~390 million years ago (Early Devonian)
	Silurian	443	Eruption of Blue Hills Volcano - 440 million years ago Avalon terrane pushes into Nashoba terrane, forming a subduction zone. Additional mylonites form between the two terranes - 443 to 417 million years ago Nahant Gabbro forms Map of the Earth ~425 million years ago (Middle Silurian)
	Ordovician	495	Formation of Quincy, Franklin, Cape Ann and Peabody granites as rifts open in Avalon. Map of the Earth ~458 million years ago (Middle Ordovician)
	Cambrian	545	Map of the Earth ~514 million years ago (Late Cambrian)
Precambrian	Proterozoic	2,500	Avalon separates from Gondwana - 550 million years ago Roxbury Conglomerate, Cambridge Sandstones and Slates form in Avalon. Mountain-top glaciers erode mountains to form Squantum Tillite - between 570 and 550 million years ago Lynn and Brighton volcanics form in Avalon - between 570 and 550 million years ago Boston Rift Basin forms in Avalon - 570 million years ago Burlington Mylonite Zone forms ~600 million years ago Map of the Earth ~650 million years ago (Late Proterozoic Era) Avalon microcontinent forms
Precambrian	Archaean	4,600	Earth forms

*There seems to be considerable debate as to the age of the Squantum Tillite - one source has its formation during Permian times; another has it forming during Precambrian times!