©  SEDIMENTARY ROCKS                 

   Rainbow bridge the largest natural bridge in the world, it is considered a sacred place by the Navajo people of the south west. It has been said if you walk under the bridge into its shadow it will bring you good luck. The bridge was known by the native peoples of the south west for many centuries but was only discovered for science in about 1908-1909 time period by William Douglass and Byron Cummings. Rainbow Bridge is composed of Navajo sandstone. Navajo sandstone was deposited in a huge desert similar to today’s Sahara desert in North Africa. The Navajo sandstone is made up of miles and miles of eolian deposited (winds blown) sand dunes. You can see the cross bedding of the ancient dunes when it was formed 200 million years ago to the right of the picture. The kayenta sandstone forms the base of Rainbow Bridge.

 
      Below a cross section of an alluvial fan near Wendover , Utah. The sediments are cross bedded and were deposited near the shore of Lake Bonneville around 20,000 years ago and later after the lake had dried up to become the present Great Salt lake

Chalcedony (microcrystalline quartz) some times called flint

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