Geology Reference
In-Depth Information
Ages in millions of years
Helium method Lead method
Pliocene
Miocene
Oligocene
Eocene
Oregon 13
Oregon 18
Germany 32
34 Mexico, Idaho
70 Colorado
New Mexico 83
Nevada 96
Nevada 107
Cretaceous
- - -100 million years
123 Japan
Jurassic
Nova Scotia 155
New Jersey 161
Connecticut 165
New Jersey 175
Triassic
200 million years - - -
Permian
Massachusetts 224
Shropshire 234
220 Norway, Bohemia
232 Carolina
Carboniferous
Shropshire 254
269 Silesia
278 Connecticut
Devonian
Massachusetts 292
- - -300 million years
Silurian
Pennsylvania 345
349 Massachusetts
Ordovician
Pennsylvania 365
366 New York
371 Connecticut
395 Sweden
405 Sweden
400 million years - - -
Cambrian
Virginia 427
Virginia 453
William Urry's 1936 helium results
Holmes compared these with world-wide lead results in his 1937
edition of
Age of the Earth
.
