It is not so much the shape that makes this building unique, but
its on-of-a-kind building material. It is petrified wood! The
location is Petrified Forest National Park, where, 225 million
years ago, a lot of tall trees were washed into a floodplain, where
a mix of silt, mud and volcanic ashes buried the logs. The sediment
cut off oxygen and slowed the logs decay. Silica-laden groundwater
seeped through the logs and replaced the original wood tissues with
silica deposits. Eventually the silica crystallized into quartz,
and the logs were preserved as petrified wood. Since the quartz
rock of the petrified logs was a lot sturdier than all the other
building materials (clay and sand stone), petrified wood was an
obvious choice.
The structure in this picture, called Agate House, is a partial
reconstruction of an Indian pueblo built here almost ten centuries
ago. It was built of petrified wood and sealed with mud mortar.
Archaeologists believe the original eight-room pueblo was built
between A.D. 1050 and 1300. |
