What a great scene reflecting everything about this park.

What later became northeastern Arizona was a low plain flanked by mountains to the south and southeast and a sea to the west. Streams flowing across the plain from the highlands deposited inorganic sediment and organic matter, including trees as well as other plants and animals that had entered or fallen into the water.

Although most organic matter decays rapidly or is eaten by other organisms, some is buried so quickly that it remains intact and may become fossilized. Within the park, the sediments containing the fossil logs for which the park is named are part of the Chinle Formation.