So what is Petrified
Well according to wikki it is "In geology, petrifaction,
petrification or silicification is the process by which organic
material is converted into stone by impregnation with silica. It is
a rare form of fossilization. Petrified wood is the most well known
result of this process, but all organisms from bacteria to
vertebrates can be petrified." and this earthcache is a prime
example of what petrified wood is.
How Does Wood Petrify
Wood must first be covered with such agents as volcanic ash,
volcanic lava flow, volcanic mud-flows, sediments in lakes and
swamps or material washed in by violent floods - by any means which
would exclude oxygen and thus prevent decay. A number of mineral
substances (such as calcite, pyrite, marcasite) can cause
petrification, but by far the most common is silica. Solutions of
silica dissolved in ground water infiltrate the buried wood and
through a complex chemical process are precipitated and left in the
individual plant cells. Here the silica may take a variety of
forms; it may be agate, jasper, chalcedony or opal. The beautiful
and varied colors of petrified wood are caused by the presence of
other minerals that enter the wood in solution with the silica.
Iron oxide stains the wood orange, rust, red or yellow. Manganese
oxide produces blues, blacks or purple.
What turned the wood to stone?
Petrified wood has been preserved for millions of years by the
process of petrification. This process turns the wood into quartz
crystal which is very brittle and shatters. Even though petrified
wood is fragile, it is also harder than steel.
Petrified wood is known for it's exquisite color and detail.
Some pieces of petrified wood have retained the original cellular
structure of the wood and the grain can easily be seen. Petrified
wood can be found throughout the desert regions. It is easy to find
and identify. It is used often in jewelry making and for other
types of decorative artwork.
What is petrification?
The process of petrification begins with three raw ingredients:
wood, water and mud. Petrification of the wood found in the
Petrified Forest began during the Triassic Period when the
primitive confers fell to the ground and into the waterways on a
journey through time. The logs were swept and tumbled downstream
with sediment and other debris. The streams traveled through a
plain of lakes and swamps were wood, sediment and debris were
deposited along the way.
In fact, 400 feet of sediments were deposited in the plain by
the rivers that originated from the volcanic mountain range. The
layer of sediments is known today as the Chinle Formation. As the
logs were deposited in the plain they were buried with mud, water
and debris. This is when the petrification process began. The mud
that covered the logs contained volcanic ash which was a key
ingredient in the petrification process. When the volcanic ash
began to decompose it released chemicals into the water and mud. As
the water seeped into the wood the chemicals from the volcanic ash
reacted to the wood and formed into quartz crystals. As the
crystals grew over time, the wood became encased in the crystals
which over millions of years, turned the wood into stone.
What are the Variables Involved in Petrification?
1.The tissue systems of the plant
2. Temperature.
3. Minerals necessary for the process of silification or
calcification
4.Duration of chemical activity
5.The nature of the embedding rock material
How long does it take to pertify?
How long it takes for petrification to occur depends on factors
such as pH and temperature, but all things being equal, groundwater
saturated with calcium carbonate (calcite) acts the fastest because
calcite is more soluble than silica or other petrifying minerals.
So if we accept the fact that petrification occurs as a continuum
(in other words, a gradual process from partial to complete
replacment/recrystallization/permineralization) Under ideal
chemical conditions, petrification is possible in a few hundred
years or even less.The tree must be sealed from oxygen to prevent
decay. if it is not sealed bacteria will usually decompose the
wood.
How to get credit for the earthcache
1.) What are the years on the two plaque that stand before?
2.) What colors do you see and explain what mineral that
they
might be to you best knowledge?
3.) What is the height of both these pieces of wood and
then
explain how they became this way?
4.) Who donated them to this park?
Finally if you like to post a picture along with your
log
then please feel free to do so
