Green River Fossil Excavation in Bonanza, UT
October 10-15, 2002

The goal of this dig was to collect fossils for a new exhibit at the Utah Field House of Natural History State Park in Vernal, Utah.  Dr. Kirk Johnson, Curator of Paleontology at the Denver Museum of Nature & Science (DMNS), was the paleobotanist in charge of the dig.  The land on which we were quarrying is federally owned and is managed by the Bureau of Land Management office in Vernal.  The quarry effort was authorized by a BLM permit issued to the DMNS.  As part of this effort, there was a film crew on site to capture footage of the excavation to be included in the new exhibit.

The goal of this research excavation was to make an extensive collection of fossil leaves, for two purposes.  The first was to collect specimens of common but spectacular leaf fossils for display in the Utah Field House of Natural History State Park.  This museum is expanding into a new building, and plans to build an exhibit devoted to the Green River Formation.  The exhibit will contain a 24 x 12 foot wall of fossil leaves containing the most common leaf types on rectangular rock tiles (The Great Wall of Vernal). The second purpose was to obtain rare specimens from the Upper Parachute Member of the Green River Formation for research being conducted presently at the Denver Museum of Nature & Science.  These specimens will be illustrated in an atlas on the Parachute Creek Member of the Green River Formation to be published by the DMNS (for a description of this atlas, see below).

Cooperating institutions and key contacts:

  • Denver Museum of Nature & Science - Dr. Kirk Johnson
  • Utah Field House of Natural History State Park - Dr. Steve Sroka, Director
  • State of Utah Parks - Karen Krieger (Karen coordinated the camp food. Thanks!)
  • The Portico Group - Allison CraigSundine
  • AJC Architects - Paul Brown
  • Bureau of Land Management, Vernal Office - Blaine Phillips

  • Note regarding fossils:  When known, each image has a caption containing its species, family and morphotype number.  For example:
    Sterculia coloradensis
    Morphotype ID: PC003




    Dig Participants
    Paul, Michele, Ben (13 yr old) Brown
    AJC Architects
    Jill Jones
    AJC Architects
    Mariann Goldthorpe
    AJC Architects
    Jeff Nielson & family
    AJC Architects
    Rob & Leticia Fornatero
    AJC Architects
    Lloyd, Val, Glade Gunther
    Brigham, UT
    Brandon Budd Herriman, UT
    Tom Cunningham Vernal, UT
    Josh Wilde Vernal, UT
    Paul Greenhalgh Brigham City, UT
    Marvin, Jaime, Danielle, and Erica Hawkins Tremonton, UT 
    Kirk Johnson
    Denver Museum of Nature & Science
    Richard Barclay
    Denver Museum of Nature & Science
    Michele Reynolds
    Denver Museum of Nature & Science
    Nicole Boyle
    Denver Museum of Nature & Science
    Steve Wagner
    Denver Museum of Nature & Science
    Ray Bridge
    Denver Museum of Nature & Science
    Mary Miller
    Denver Museum of Nature & Science
    Norma Neyman
    Denver Museum of Nature & Science
    Alison Sampson
    Denver Museum of Nature & Science
    Gary Raham
    Denver Museum of Nature & Science
    Michael Rinne
    Denver Museum of Nature & Science
    Susan Hill Newton Denver Museum of Nature & Science
    Kirsten Johnson
    Film Crew, Brooklyn, New York
    Gabriel Miller
    Film Crew, Brooklyn, New York
    Darrald & Allison CraigSundine
    Portico Group, Seattle
    Charles Mayes Portico Group, Seattle
    Sherry Smith
    Seattle, WA
    Matt Huston & Sam (5 yr old)
    Seattle, WA
    Karen Kreiger
    Utah State Parks
    Mike Cram
    Utah State Parks
    Dena Loyola
    Utah State Parks
    Terry Martin
    Utah State Parks
    Gary Thorson Utah State Parks
    Steven D. Sroka
    Utah Field House of Natural History
    Danny, Lindi, Benjamin, Melissa, Donovan, Dalin, and Caleb Anderson
    Utah Field House of Natural History
    Northeastern Utah Visitor Center
    Nada Murray
    Utah Field House of Natural History
    Laurie Stickler
    Utah Field House of Natural History
    Coleen Lawson Northeastern Utah Visitor Center
    Linda Clawson Northeastern Utah Visitor Center

    The Parachute Creek Atlas Project:
    A plan to document the megaflora of the Green River Formation
    from Colorado and Utah and to publish this atlas as a
     Proceedings of the Denver Museum of Nature & Science.

    Project team members:
    Kirk Johnson, William Bateman, Michael Graham, Rich Barclay, Nicole Boyle
    Denver Museum of Nature & Science

    Steven Manchester
    Florida Museum of Natural History

    Bruce Handley
    Pleasant Hill, California

    August, 2002

    The Middle Eocene Parachute Member of the Green River Formation is widely exposed in the Piceance Creek and Uinta Basins of Colorado and Utah. This unit has been a major focus of oil shale exploration and represents a maximum high stand of Lake Uinta. A widespread organic-rich marker bed, the Mahogany Bench (and Mahogany Marker) allows for regional stratigraphic control. Most of the published paleobotanical reports from the formation discuss fossils from the vicinity of the Mahogany Bench. These fossils are much younger and considerably different from the fossils from the fish-bearing Green River Formation from Fossil Lake near Kemmerer, Wyoming. Parachute Creek sites primarily produce fossil plants and insects but fish, birds, lizards, and other vertebrates are occasionally recovered. The flora and fauna from this unit enjoy huge popular interest and the collecting sites near Bonanza, Utah and Douglas Pass, Colorado are internationally known.

    Despite this interest, no single collection or monograph adequately represents the diversity of the Parachute Creek assemblage, which has not been studied since MacGinitie (1974). There are a number of interesting questions about the age and nature of the vegetation and its paleoclimatic and paleoenvironmental significance. To document the relative abundance of common species, we excavated a quarry near Bonanza in 1996. The resulting collection of 989 identifiable specimens represents 48 species. The most common genera are Parvileguminophyllum (27%), Cedrelospermum (25%), Macginitiea (8%), Rhus (7%), Allophylus (6%), Caesalpina (4%), and Cardiospermum (4%) (Wilf et al., 2001; Johnson et al., 2002) . This flora represents material that has been transported as far as 40 km from the source vegetation, as calculated by the position of the fossil quarry relative to the lake margin. The distribution of plant parts so far from the shoreline remains an interesting taphonomic problem that greatly complicates reconstruction of the ancient lake margin vegetation. Conversely, this high degree of transportation allows for the preservation of an extremely diverse paleoflora.

    Due to the popularity of the Bonanza and Douglas Pass sites, we perceive a need and a demand for a comprehensive atlas of the flora. Such an atlas would be useful for amateur collectors because it would allow them to identify their fossils. It would be useful for land managers because it would help them to define the scientifically significant and rare fossils. Fossils that are significant include not only the rare species but also common species preserved in botanical attachment. For example, Macgintiea leaves and fruits are both common but they have never been found attached. Scientists would benefit by having a more educated collecting public who could then recognize rare specimens and donate them to research museums. A book on the Green River fish (Grande, 1984) has been very successful and has been reprinted many times by the Wyoming Geological Survey.

    Recent developments in the study of leaf architecture (LAWG, 1999) provide a terminology for this atlas and the Denver Museum of Nature & Science has been collecting and borrowing specimens with this project in mind. To date, we have surveyed a number of public and private collections and have recorded approximately 200 species from the Parachute Creek Member. The Denver Museum of  Nature & Science Proceeding Series is the proposed publication venue. DMNS Proceedings have recently been published on the flora of the Hell Creek (Johnson, 1996) and Florissant Formations (Evanoff et al., 2001), establishing this series as one known for paleobotanical topics.

    At present, the volume is projected to contain photographs of all common and rare plant species and such diagnostic information as to allow the reader to identify their fossils.

    Preparation of the manuscript should be complete by May, 2003, allowing for publication by September, 2003.

    Evanoff, E., Gregory-Wodzicki, K. M., and Johnson K. R., 2001, Fossil flora and stratigraphy of the Florissant Formation, Colorado, Proceedings of the Denver Museum of Nature & Science, series 4, no. 1, 218 p.
    Grande, L., 1984, Paleontology of the Green River Formation, with a review of the fish fauna: Geol. Surv. Wyo. Bull., v. 52, p. 333.
    Johnson, K. R., 1996, Description of seven common plant megafossils from the Hell Creek Formation (Late Cretaceous: late Maastrichtian), North Dakota, South Dakota, and Montana).  Proceedings of the Denver Museum of Natural History, series 3, no. 12, 48 p.
    Johnson, K. R. 2002, in press, The Parachute Creek Atlas Project: An Overview of the Megaflora of the Green River Formation from Colorado and Utah. Geological Society of America Abstracts with Program v. 34, no. 6, p. 480.
    Johnson. K. R. and Plumb, C., 1995, Common plant fossils from the Green River Formation at Douglas Pass, Colorado, and Bonanza, Utah in W. R. Averett (editor), The Green River Formation in the Piceance Creek and Eastern Uinta Basins, Grand Junction Geological Society Guidebook, p. 121-130.
    Leaf Architecture Working Group, 1999, Manual of Leaf Architecture - morphological description and categorization of dicotyledonous and net-veined monocotyledonous angiosperms. 65 p., Washington, D. C., ISBN 0-9677554-0-9.
    MacGinitie, H. D., 1969, The Eocene Green River flora of northwestern Colorado and northeastern Utah: Univ. Cal. Pub. Geol. Sci., v. 83, p. 140.
    Wilf, P., Labandeira, C.C., Johnson, K.R., Coley, P. D., and Cutter, A. D., 2001, Insect herbivory, plant defense, and early Cenozoic climate change. Proceedings of the National Academy of Sciences USA, v. 98, p. 6221-6226.
    [Created 10/17/2002]
    [Last Updated: 06/01/2003]