Transcript California Geologic History

California Geologic History
Simplified and related to the Monterey
Bay and Canyon Formation
Part 1
Introduction
 The earth is very old – 4.5 billion years old
 Most of California of relatively new
 The mountains are still changing, and most
features are very young (geologically)—only a
few million years old.
 The earth’s solid surface (crust) is active and
broken into pieces called plates, which slide
slowly over the soft layer (Asthenosphere)
Plates
 Current plates and boundaries
Types of Plate Boundary
Ca Geology
 Extremely complex
 Only a few
fragments of rocks
older than 500
million years
500 million
years ago
 California, Oregon
and Washington
were still ocean
Dinosaur Era 245-65 mya
(Mesozoic)
The Sierra Nevada Mountains were pushed up
(uplifted) by the formation of the granitic rocks
underground
 The ocean plate continues to push under North
America adding a series of slices of old sea floor
to the land.

California
stages
170 mya - no central
valley or coast range
130 mya - central
valley is a sea, and
coast ranges are
starting
40 mya - central valley
is dry.
Coast ranges bigger
and higher
Evidence
 The slices which
were pushed
onto Ca
contained special
deep mantle
rocks rarely
found on land.
 These are purple
on this map
By 100 Million years
ago the spreading
centers off the Ca
coast were getting
closer to the
subduction zone.
The spreading
centers formed a
series of underwater
mountains including
the Davidson
Seamount