Geology of the Feather Geology of the Feather RiverRiver

Where does one start?Where does one start?

NERDS 2006NERDS 2006

Teresa KennedyTeresa Kennedy

Some UnderstandingsSome Understandings

Plate Tectonics (which is different from Plate Tectonics (which is different from continental drift)continental drift)

Subduction results in remelted material Subduction results in remelted material (magma) which rises because it is less (magma) which rises because it is less dense to form new crustdense to form new crust

Plate margins are places of brittle and Plate margins are places of brittle and ductile deformationductile deformation

The past is the key to the present…The past is the key to the present…geologic processes are dynamicgeologic processes are dynamic

Geologic Time ScaleGeologic Time Scale

Four Major Eras:Four Major Eras: Precambrian: Age of AlgaePrecambrian: Age of Algae Paleozoic: Age of FishPaleozoic: Age of Fish Mesozoic: Age of DinosaursMesozoic: Age of Dinosaurs Cenozoic: Age of MammalsCenozoic: Age of Mammals

OverviewOverview

Igneous, metamorphic, and sedimentary Igneous, metamorphic, and sedimentary rocksrocks

Some tilted, some flat-lyingSome tilted, some flat-lying Submarine and subaerial rocksSubmarine and subaerial rocks Much of the rock record missing due to Much of the rock record missing due to

erosionerosion FossilsFossils Heavy vegetationHeavy vegetation GlaciationsGlaciations

PrecambrianPrecambrian

~ 4.5 billion years ago~ 4.5 billion years ago Until 544 million years ago…Until 544 million years ago… Feather River area was at the bottom Feather River area was at the bottom

of the oceanof the ocean No rocks this old are exposed No rocks this old are exposed

anywhere close to there!anywhere close to there!

PaleozoicPaleozoic

544 million years to 255 million years ago544 million years to 255 million years ago Western margin of North American craton Western margin of North American craton

was 600 – 700 miles to the eastwas 600 – 700 miles to the east 20,000 – 30,000 feet of rock deposited in 20,000 – 30,000 feet of rock deposited in

deep oceandeep ocean Chert (formed from radiolaria)Chert (formed from radiolaria) Volcanic ash and breccia from volcanoes Volcanic ash and breccia from volcanoes

caused by subduction to west.caused by subduction to west.

MesozoicMesozoic

225 million years to 65 million years225 million years to 65 million years Deformation: folding and faulting Deformation: folding and faulting

from collision with other crustal from collision with other crustal piecespieces

Layers tilted up to 60 degreesLayers tilted up to 60 degrees Metamorphism from igneous plutons Metamorphism from igneous plutons

rising from subducted magma.rising from subducted magma. Oldest plutons are to the westOldest plutons are to the west

CenozoicCenozoic

65 million years to present65 million years to present Modern volcanic activity related to Modern volcanic activity related to

spreading of Basin and Rangespreading of Basin and Range Crest of Sierra Nevada is to the westCrest of Sierra Nevada is to the west UpliftUplift

• ErosionErosion• Change in climateChange in climate

GlaciersGlaciers• ErosionErosion• Changes in drainage, soils, vegetationChanges in drainage, soils, vegetation