Araucarioxylon arizonicum
(ca. 250 x 300 mm)
petrified wood 2: North Amerika (Arizona, Utah)
2. Arizona
The state of Arizona is famous because of
the Petrified Forest National Park. Petrified wood from this area reside in
collections worldwide. The area of Arizona contained within the Petrified Forest
National Park was once part of a large forest that extended from Texas into
Utah.
225 million years ago in the late Triassic this high dry tableland was once a
vast floodplain crossed by many streams. The trees- Araucaria,
Woodworthia and Schilderia- fell and were washed by swollen streams
into the floodplain. There they were covered by silt, mud, and volcanic ash, and
this blanket of deposits cut off oxygen and slowed the logs' decay. Gradually
silica bearing ground waters seeped through the logs, and bit by bit, encased
the original wood tissues with silica deposits. Much later the whole area was
uplifted and eroded. Today the ever present forces of wind and water continue to
remove sediments. Erosion continues to break down the giant logs and reach for
the logs and other remaining fossils still buried below the surface. Arizona produces some of the most colourful woods.
Because of the brightly colouration the wood is also known as “rainbow
wood”. The usual colour of the wood is red, with yellow, black and white bands
although shades such as blue are often found. The wood may be collected
over a large area of east central Arizona but only outside of the National Park.
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Something special is the green
coloured wood made of the mineral chromium. This very rare petrified wood comes
from a small isolated deposit in the upper Chincle formation of northern
Arizona, near Winslow (Mackleprang). Two percent of chromium is responsible for the rich green
colour. The species of this wood is known as Araucarioxylon Arizonicum.
 green wood (Mackleprang Wash) (ca. 100 x 100 mm) |
3. Utah
The most known places for collecting petrified wood in Utah are „Henry
Mountains“ and „Escalante“. The combination of the black and yellow colours
(Henry Mountains) are unique. The wood of this regions is very colourful, too.
The wood called “red wood” are gems of carnelian agate. This wood doesn't even
look like wood-it looks more like agate but is very beautiful. The agate casts
do not have any of the original woody textures, thus making identification
impossible. Limb casts,
probably of conifer wood, found initially and most prolifically in the Yellow
Cat area of Grand County, Utah, are among the world's most beautiful examples of
agate fortification wood. "Red wood," as it is called by local collectors,
occurs as limb casts containing red-banded agate with accents of white, grey,
black, yellow, orange, blue, and violet. This rare material has been collected
for more than seventy years and, because of its beauty, is much sought after by
local collectors of fossil wood. The name red wood is purely a colour
description and a colloquialism.
Red wood has been found outside the Yellow Cat
area at a number of locations but always in sediments of the brushy Basin Member
of the Morisson Formation. Localities are known from northeast of Moab, west to
the green River, south to the Dolores River, and even further south-west to
areas around the Henry Mountains.
Yellow Cat Red Wood
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