Geologic History of New York

Eras and periods, index fossils, NY surface bedrock, landscape regions, and geologic time scale.

Geologic History of New York State

Chronology of Earth’s history divided into eons, eras, periods, and epochs with index fossils and major tectonic events in NY.

Reference Table p. 6

1
Eras from oldest to youngestPaleozoic, Mesozoic, Cenozoic
2
Longest time spanPrecambrian time (~4 billion years, 88% of Earth’s history)
3
NY State FossilEurypterus remipes (Silurian Period)
4
Dinosaur extinction eventMesozoic–Cenozoic boundary (~66 million years ago)
5
Index fossil requirementLived for a short geologic duration but had wide geographic distribution

Surface bedrock maps and geographic provinces of New York State. Rock age and structure determine landscape topography.

Reference Table p. 8

1
Oldest NY surface bedrockAdirondack Mountains (Precambrian metamorphic/igneous)
2
Plains and lowlands structureFlat-lying sedimentary rock with low elevation and relief
3
Principle of SuperpositionIn undisturbed sedimentary strata, oldest layer is at the bottom
4
Cross-cutting relationshipsAn igneous intrusion or fault is younger than the rocks it cuts across