petrified forest

Petrified ForestBy A.J. , Javier , And Isaiah S.

Facts

It was made a national park on 1906 to protect the petrified wood for its scientific value.

The park overs about 146 square miles.

The forest average about 5,400 ft. in elevation and has a dry windy climate with temperatures that vary from 100 degrees in summer and well below freezing in winter.

There is about 400 species of plants in the national park.

The national park is located in Arizona of the Apache and Navajo counties

Its known for its fossils, especially trees that lived in the late Triassic period, about 225

million years ago.

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How they formed ?

Almost 60 million years ago, there was pressure in the earth that caused the land containing Petrified Forest to bulge upward, forming hills of sandstone, siltstone, mudstone, and clay. In these hills, which had once been on the floor of the marsh, lay thousands of petrified trees and fossils. Erosion then began to eat away at hills that were exposed. Rain, snow, and ice, the (main elements of erosion) broke the soft stone into individual stones. Water and wind carried that rock.

Fossils

The buried trees lay underneath the ancient marsh sediment for millions of years. The deposits grew thicker until the logs were buried 1500 feet(457miles) deep. Many marsh animals died by being buried in sediment and were fossilized just like the trees. Some of the animals including insects are snails clams crabs fish amphibians reptiles and dinosaurs. The biggest animal found was the Phytosaurs that looked like a crocodile. It had snaggly teeth and grew up to 30 feet long

Phytosaur

Phytosaur (alive)

How petrifaction works

When trees died they were washed away by streams into marshes. They sank to the bottom of the marshes and were covered by sediment. Nearby volcanoes erupted tons of ash. It dissolved into the marsh soaking into the sediment and into the trees. Volcanic ash has a mineral called silica and as the wood rotted away it was replaced by silica absorbed by the water. When the marsh dried up the silica hardened into a stone called quartz

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