Paleontology and geology
The Precambrian: Precambrian rocks in New Hampshire are predominantly metamorphic, and do not contain fossils.
The Paleozoic: There are no fossiliferous rocks from the Paleozoic in New Hampshire. Rocks formed in the early part of the Paleozoic (Cambrian through Silurian) are entirely metamorphic and igneous and do not contain fossils. However, evidence from neighboring states suggests that a shallow sea covered the state during this time. During the Devonian, an episode of mountain building strongly affected New Hampshire, metamorphosing rocks formed earlier in time. There are no Carboniferous or Permian rocks in New Hampshire, as this was a time of uplift and erosion in the state.
The Mesozoic: During the Mesozoic, the state was above sea level, and erosion outpaced deposition during this time interval. Therefore, there are very few Mesozoic rocks in New Hampshire. The few Mesozoic rocks that can be found in the state are entirely igneous, and are probably related to continued rifting of the supercontinent of Pangea. They contain no fossils.
The Cenozoic: New Hampshire was above sea level during the Tertiary, and erosion outpaced deposition. During much of the Quaternary, thick sheets of ice covered the state. Sediments deposited by the melting ice or during warmer intervals between glacial advances can be found throughout the state. Plant and pollen fossils in some of these sediments indicate that species of plants now common to arctic Canada grew in the area during periods of glacial retreat.