Do Not Migrate
Three petrified wood tree stumps

Stump Trio P20 at Florissant Fossil Beds National Monument, Colorado enclosed in temporary Yurts, 1997 (NPS Archive)

This research report assesses the structural decay of nine silicified fossil stumps on the Petrified Forest Loop at Florissant Fossil Beds National Monument in central Colorado, and evaluates the use of mechanical pinning
as a remedial conservation treatment. Condition assessment was established through an integrated review of archival documents related to the site’s excavation and display history, field examination, and petrographic analysis, among other laboratory characterizations. The story of this fossil forest begins with the violent burial of a Sequoia affinis paleo-forest from a volcanic mudflow (lahar) and subsequent cycles of lacustrine submerging and desiccation which likely caused organic materials to alternately rot and silicify. As part of the geological record, these stumps underwent immense pressure,mineralization, and seismic trauma. By the late nineteenth century settlers and early paleontologists began to excavate the stumps, sometimes by dynamite, and pilfer wood alongside the area’s famous fossil-laden shale beds. A popular tourist site for collection and display, the site was ultimately acquired and protected by the National Park Service, and today is one of the most important paleo-forest parks in the world. A highlight of visitation, many stumps are actively deteriorating as a result of complex mechanisms resulting in active detachment and loss. Reversible mechanical pinning offers a viable method of remedial structural repair to the stumps’ delaminating lamellar fabric with minimal compromise to the their primary value as a significant paleontological resource.

National Center for Preservation Technology and Training
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