The plant fossils that you see at this location are called sabalites. These fossilized palm leaves were collected from siltstone rocks of the Chuckanut Formation near Bellingham WA in the 1960s. These fossils are examples of the palm genus Sabalites (the sabal or palmetto palm).
These plants grew in a lowland enivornment along coastal Washington about 55 million years during the late Paleocene era. The plant fossils from this period have been interpreted as subtropical vegetation. There were a few different kinds: angiosperms, metasequoia, sabalites, glyptostrobus, and warm-climate ferns. These plants tell us that the region was significantly warmer during this timeframe, about 27 degrees warmer than today.
So how did this fossil form?
This area was a fluvial plain of deposited sediment, much like a river delta today. It will drop silt and other sediment as the water slows down. For over 22 million years, this silt, sand, and sediment was deposited and then hardened into layers of sandstone, siltstone, and shale. These layers are estimated at 20,000 feet deep in some areas!
Since this area was subtropical, many plants and animal life were here. After being covered by the layers of sediment that hardened, many fossil fronds and trunks are found in the rocks. Palm frond imprints have been identified in this area: sabalites cambelli and sabalites ungeri.
As the palms fell to the bottom of the water, they were covered by more layers of sand. As the palms rotted, it would leave an imprint in the sand. As the layers hardened, the fossils were preserved in the rock layers. This is called an impression fossil.
The other type of fossil would be a compression fossil. Part of the palm would stay there stuck in the rock. The pressure of the forck forming would slowily turn the palm into pure carbon. And since the carbon will not rot, it would stay there in the rock just like any other piece of rock.
Logging tasks:
1. How many sabalite fossils do you see here?
2. Explain in your own words how they formed.
3. What type of fossil do you think they are: compression or impression? Explain why.
4. Do you see any other fossils in the rock?
5. Post a picture of yourself (face not required) or a personal item at the site.
Sources:
https://www.dailykos.com/stories/2013/9/29/1238885/-Fossils-and-pseudofossils-in-the-The-Chuckanut-Formation-Part-1-flora
https://en.wikipedia.org/wiki/Sabalites
https://sciencing.com/types-of-plant-fossils-12003853.html
Burke Museum staff