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?

 

HypothesizeIf 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?

ImagineImagine 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

1. The tissue systems of the 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

In 1906 Professor Wieland created a theory on the

petrification process of wood based on five variables:

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 worldPetrified 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

• In 1915, the German geologist and meteorologist Alfred Wegener (1880-1930) 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.

MineralsPetrified 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?

• 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 Together245-208 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 Period144-66.4 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.