Transcript Imagine

Petrified Wood
Welcome!
As we examine the
process of petrification,
you as an acting scientist
will be able to analyze
and manipulate data, to
predict conditions
favorable towards the
petrification process, to
speculate on the species
and the involved
variables of petrified
pieces, and to solve a
mystery with one piece of
evidence.
The Fascination
Native people alleged that the petrified logs found in
Arizona were spent arrow shafts and spears thrown
by the Thunder God Shinauav and his enemies during
a great battle. The Navajo tribe believed the
petrifications were the bones of the great monster
Yeitso. Leonardo Da Vinci examined various petrified
minerals and created his theories of the creation of
the Earth. Charles Darwin was interested in the
petrified wood while exploring in Argentina
speculating on the plant’s form prior to petrification.
There have been many scientists fascinated with the
secrets of the petrified pieces.
Petrified Wood
When a fossil, a skeleton of the
ancient world, is discovered it
enables scientists and
mathematicians to better
understand the mysteries of the
ancient world. A fossil is an
image or object that allows us to
develop a better understanding of
geology, mineralogy, paleobotany,
paleontology, chemistry, biology,
evolution, and many other
mathematic and scientific areas.
Over the millions of years many
species of trees have existed, yet
only a small fraction have
fossilized. Why?
Hypothesize
If you look around at the few
or many trees in your area,
take a moment and select a
few trees that you think
might petrify. What are the
characteristics of your
chosen few? Are the trees
similar, or are the trees
different? If you were able
to control the surroundings
of the tree to ensure
petrification, what would you
select? What are the
necessary variables for the
petrification process?
Imagine
Imagine a large basin area with a lush
landscape containing many rives and
streams flowing through the lowlands.
During the Triassic period Colorado,
Arizona, New Mexico, and Utah were
located near the equator. The land
looked much different than it does today.
Over time trees dies or perhaps were
destroyed by floodwater or wind; the
rivers then carried the trees into the
lowlands. Some trees were deposited
and buried in the stream channels. Most
trees decayed and disappeared, but
others were petrified.
The Petrification Process
As the logs were buried, the cells structure of
the trees were infiltrated with minerals and
lodged in a sedimentary source such as
sandstone, siltstone, and clay formed from
weathered volcanic ash, a key ingredient of the
petrification process. The Chinle formation,
located in the four corners area of the United
States, reveals layers of 400 feet of sediment
that were deposited by rivers that originated
from volcanic mountain ranges. As the
volcanic ash decomposed chemicals were
released and with the aid of water which
permeated the wood and formed into quartz
crystals eventually turning the wood into stone.
Petrification Variables
In 1906 Professor Wieland created a theory on the
petrification process of wood based on five variables:
 1. The tissue systems of the
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plant
2. Temperature
3. Minerals necessary for the
process of silicification or
calcification
4. Duration of chemical activity
5. The nature of the
embedding rock material
Signs of the Past
Walnut, sycamore, oak, magnolia, palm,
redwood, chestnut, and dogwood trees
are common petrified pieces found to date.
The cells structure of the trees were infiltrated
with minerals and lodged in a sedimentary
source such as sandstone, siltstone, and clay
formed from weathered volcanic ash.
If the wood is immediately subjected to
petrification, the piece retains much of the
original material. If the petrification takes
place over a long period of time the wood is
subjected to many minerals which breaks
down the material altering the appearance of
wood.
All over the world
Petrified wood can be found all
over the world. There are
certain characteristics that
enable the preservation of the
petrified pieces, such as the
Chinle Formation. Arid
conditions are optimal and
reduce the chance of decay.
Similar species of petrified
wood are found in the United
States, Australia, Argentina,
and Africa. This elicits
conjecture regarding the
original location of the trees.
Pangaea
”all the land" in Greek
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In 1915, the German geologist and
meteorologist Alfred Wegener (18801930) first proposed the theory of
continental drift, which states that parts
of the Earth's crust slowly drift atop a
liquid core. The fossil record supports
and gives credence to the theories of
continental drift and plate tectonics.
Wegener hypothesized that there was
an original, gigantic supercontinent 200
million years ago, which he named
Pangaea, meaning "All-earth". Pangaea
was a supercontinent consisting of all of
Earth's land masses. It existed from the
Permian through Jurassic periods. It
began breaking up during the late
Triassic period.
Pangaea started to break up into two smaller supercontinents,
called Laurasia and Gondwanaland, during the late Triassic. It
formed the continents Gondwanaland and Laurasia, separated by
the Tethys Sea. By the end of the Cretaceous period, the
continents were separating into land masses that look like our
modern-day continents.
Era and Periods
Geology reveals the
different periods through the
strata of color that indicate
atmospheric activity and
minerals present in the
geological constitution. The
combination of the rock and
the minerals create the
colors within the petrified
wood.
Minerals
Petrified wood is a
collection of minerals.
The majority of petrified
wood is hydrous
microcrystalline varieties
of quartz, termed as
chalcedony or opal.
Chalcedony has bundles
of silica fibers that
interlock and absorb
water. This is called
silicification. The color
of the petrified wood
reveals the minerals that
were involved creating a
rainbow of colors or lack
of within the petrified
material.
What might have coexisted with a piece of
petrified wood?
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The earliest period of the Mesozoic Era was the Triassic period (248 208 million years ago), in which the first small dinosaurs and mammals
developed. The Triassic began after a major extinction had wiped out
most of the life forms on Earth. The end of the Triassic was also marked
by a worldwide extinction, although minor in comparison.
The second period was the Jurassic period (208-146 million years ago),
in which the dinosaurs began to flourish. Giant sauropods appeared
along with many other dinosaurs. The first primitive birds and flowering
plants (angiosperms) appeared.
The third Mesozoic period was the Cretaceous period (146-65 million
years ago), which saw the height of the dinosaurs and the development
of flowering plants. It ended with another extinction and the demise of
the dinosaurs and many other prehistoric animals.
Triassic period
Earliest Dinosaurs Band Together
245-208 Million Years Ago - A
devastating mass extinction
opens the Triassic.
Dinosaurs get their start about 235 million
years ago, sharing the world with all
kinds of other giant reptiles, and even
the earliest mammals!
Mammals appeared 220 million
years ago, right alongside the
earliest dinosaurs. But when
dinosaurs went extinct, mammals
began to fill the gap.
Jurassic Period
208-144 Million Years Ago.
Supercontinent Pangea splits
further and further apart, moving
landmasses across the globe. The
biggest dinosaurs and the first
birds evolve.
This is a good picture of the wet season in
Apatosaurus' Colorado home. Apatosaurus
lived alongside 16 other kinds of dinosaurs,
including Brachiosaurus and Stegosaurus,
and 50 kinds of mammals! Also on the
prowl were crocodiles, pterosaurs and
snakes; in the rivers lived fish, turtles,
crayfish, and clams.
Brontosaurus
Cretaceous Period
144-66.4 million years ago Dinosaurs diversify like never
before, but become extinct at the
end of the Cretaceous.
As flowering plants evolved,
their blossoms added new
colors to the landscape.
Jurassic dinosaurs like
Stegosaurus saw only
green plants. 80 million
years later, Cretaceous
Triceratops walked through
fields brightened by flowers.