One can only dream of finding great fossil leaves in their own backyard. Imagine my surprise when I found fossil plants on a walk with my dog in my own neighborhood. The local water district sold their well water rights to Aurora, Co. A major construction effort is underway to lay a new water main from Centennial to Aurora, Co. I've travel all across the country to find fossils, but on my daily dog walk, I found fossil leaves in my own neighborhood from the Paleocene (65 to 54.8 million years ago). More analysis is required to determine if these fossils are from the D1 or D2 formations of the Denver Basin. The image at left is a huge Platunus marginata (note dime for scale) found during recovery efforts on 5/31/2003. Recovery of a complete specimen like this from a bulldozer pile is extremely rare. Many other specimens of Platunus and palm were found as well as those yet to be identified.
The fossil leaves where found on the surface once the water main construction effort was completed and the pipe covered. Most of the fossils were found in a light gray mudstone, while a few were in a more coarse tan/beige material (for more, see "geology" below). Both of these materials are extremely sensitive to changes in humidity and can be completely destroyed by rainfall. A major rainstorm was looming, so a friend and I frantically collected what we could from the site. The rain fell hard that evening and all fossils which remained were completely destroyed and unrecognizable.
In the following days, I went to the county assessor's office to determine who owned the land. I determined that the land was owned by the Archdiocese of Denver (co-owner Saint Thomas More Catholic Church on Quebec St.). I contacted the operations/facilities office at the Church regarding the donation of the fossils to the Denver Museum of Nature & Science (DMNS). DMNS is currently studying the fossils and geology of the Denver Basin on a multi-year grant from the National Science Foundation (NSF). This find represents another resource of fossil information. Saint Thomas More has, graciously, offered to donate the fossils to DMNS for their study. However, they want to keep a few fossils for the science teachers at their school. This is completely understandable and I will offer to give a lecture on the finds to their school. A big thanks is due to the Saint Thomas More Catholic Church for donating fossils from their land to the DMNS study. They were also very understanding in our recovery of the fossils from their land prior to the rainstorm. Saint Thomas More has been a true asset to the neighborhood and to science in this effort. Their cooperation is a valuable example of neighborhood members working together with the ultimate goal of science and learning for everyone involved. If you read this and appreciate their cooperation, PLEASE let them know - see their contact form and select the Department "Parish Office - Business Manager".
Below, you will find a link to fossil images found during the May 31, 2003 collection efforts. Some of the fossils are truly beautiful to anyone, while others are scrappy, yet still very important to researchers. All fossil images are included in the link below.
(Complete list of fossil images,
Select thumbnails to see desired image.)
For those curious about the location or geology, these fossil leaves where found on the surface after the water main was buried. GPS coordinates are N 39*34.234'; W104*54.490' (format: ddd.mm.mmm'); Elev: 5741 ft; or N 39.57057*; W104.90817* (in decimal degrees format: dd.ddddd). The water main trench at this location was at a depth of 16 feet. It's unfortunate that I could not see the trench before it was filled in again. It would have provided valuable information on the layers described below.
The fossil leaves appear to have been preserved in three different depositional sequences. Most often leaves are preserved in a river or lake environment with the help of hard rains and/or flooding. For more on this, see the pages in the Castle Rock Fossil Rainforest section on "Making of a Fossil Rainforest" and "The Meandering River".
Three Depositional Sequences:
- Light gray mudstone, grains very fine-to fine, well-sorted, well rounded, with mudstone layers typically measuring 1-2 cm between leaf layers.
- Light gray/tan mud/sandstone, more sandy than above, some mica and dark gray grains, finely grained not well sorted, rounded. Blocks of leaf mat (many layers of leaves, one on top of another).
- Beige sandstone, much more sandy than above and filled with mica and dark gray grains, mostly fine-to medium, not well sorted, subrounded to rounded.