Geology of the Feather River

1
Geology of the Feather River

• Where does one start?
• NERDS 2006
• Teresa Kennedy

2
Some Understandings

• Plate Tectonics (which is different from
  continental drift)
• Subduction results in remelted material (magma)
  which rises because it is less dense to form new
  crust
• Plate margins are places of brittle and ductile
  deformation
• The past is the key to the presentgeologic
  processes are dynamic

3
Geologic Time Scale

• Four Major Eras
• Precambrian Age of Algae
• Paleozoic Age of Fish
• Mesozoic Age of Dinosaurs
• Cenozoic Age of Mammals

4
Overview

• Igneous, metamorphic, and sedimentary rocks
• Some tilted, some flat-lying
• Submarine and subaerial rocks
• Much of the rock record missing due to erosion
• Fossils
• Heavy vegetation
• Glaciations

5
Precambrian

• 4.5 billion years ago
• Until 544 million years ago
• Feather River area was at the bottom of the ocean
• No rocks this old are exposed anywhere close to
  there!

6
Paleozoic

• 544 million years to 255 million years ago
• Western margin of North American craton was 600
  700 miles to the east
• 20,000 30,000 feet of rock deposited in deep
  ocean
• Chert (formed from radiolaria)
• Volcanic ash and breccia from volcanoes caused by
  subduction to west.

7
Mesozoic

• 225 million years to 65 million years
• Deformation folding and faulting from collision
  with other crustal pieces
• Layers tilted up to 60 degrees
• Metamorphism from igneous plutons rising from
  subducted magma.
• Oldest plutons are to the west

8
Cenozoic

• 65 million years to present
• Modern volcanic activity related to spreading of
  Basin and Range
• Crest of Sierra Nevada is to the west
• Uplift
• Erosion
• Change in climate
• Glaciers
• Erosion
• Changes in drainage, soils, vegetation