Abstract
The 1895 discovery of a petrified tree near Clover Creek in south-central Idaho, USA, attracted worldwide attention and resulted in the naming of a new species of ancient oak, Quercinium pliocaenicum Schuster. For more than a century, the discovery has largely been forgotten, even though specimens reside in reputable museums. Reinvestigation of the locality in 2014/2015 resulted in newly-collected specimens and a wealth of new data. Optical microscopy confirms the cellular anatomy used for the original taxonomic study. X-ray diffraction, scanning electron microscopy, energy-dispersive electron spectroscopy, Raman spectroscopy and cathodoluminescence microscopy reveal details of the mineralization, showing the presence of opal-CT as the primary component, with chalcedony as a lesser constituent. This mineralogy suggests petrifaction occurred in at least two stages, beginning with opalization of cellular tissue, leaving open vessels that became filled with chalcedony during a later mineralization episode. Clover Creek oak represents relict flora growing in a wetter climate before the uplift of the Cascade Range created a rain shadow that caused profound desertification of the inland Pacific Northwest.
Highlights
This report describes the rediscovery of a historic North American fossil wood locality, its geologic setting and a detailed re-examination of newly-collected specimens using a variety of petrographic and geochemical methods.In 1895, land surveyors working 11 km northwest of Bliss, Idaho, discovered intact branches of a fossil tree protruding a meter above the ground surface [1]
Clover Creek opalized wood is displayed as a mineral variant instead of a fossil in major museums in the U.S, Canada and Europe, even though the mineral dealer Foote [2] described the specimen as
Historical research uncovering the provenance of museum specimens, rediscovery of Schuster’s original thin section slides, along with rediscovery of the original site and the collection of new specimens allowed for a thorough scientific investigation of the geologic setting and wood mineralization
Summary
This report describes the rediscovery of a historic North American fossil wood locality, its geologic setting and a detailed re-examination of newly-collected specimens using a variety of petrographic and geochemical methods. In 1895, land surveyors working 11 km northwest of Bliss, Idaho, discovered intact branches of a fossil tree protruding a meter above the ground surface [1]. The fossil tree was believed to be standing where it grew, and no other fossil wood was found in the vicinity. Geosciences 2016, 6, 21; doi:10.3390/geosciences6020021 www.mdpi.com/journal/geosciences were shipped to Philadelphia mineral dealer A.E. Foote by 1897 [1]. All Foote labels corresponding to wood were shipped to Philadelphia mineral dealer A.E. Foote by 1897 [1]. All Foote labels the Clover Creek material bear the number 212 [2] as a reference to opal’s order in the sixth edition of corresponding to the Clover Creek material bear the number 212 [2] as a reference to opal’s order in
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