Palm WoodKingdom: Plantae
Sub Period: None
International Age: Tortonian
Contra Costa Group
Collector: DPS Ammonite
Acquired by: Field Collection
Length: 120 mm
Width: 83 mm
Thickness: 43 mm
Contra Costa County
This is a piece of late Miocene palm “wood” from Orinda, California. Not a true wood; it is part of the Palmoxylon form genus. Palm wood can rarely be attributed to a palm species identified by foliage or fruit such as Sabal.
It was found in a landslide area on top of sedimentary interbeds of the Moraga Formation and the younger lacustrine Siesta Formation sediments. Volcanic rocks and possible spring deposits are nearby. Fossilized palm roots, reeds and petrified wood occur in the area.
This piece and others found in the area represent the youngest palm fossils found in Northern California. Cretaceous and Eocene palm fossils are found in Northern California and to the north in Oregon and Alaska. Drying and cooling conditions in the Miocene pushed palms further south where they are found in the Dove Spring Formation near Rosemond, the Barstow Formation near Calico and the Bopesta Formation in the Tehachapi Mountains.
The silicified layered coatings on the wood may be spring deposits or stromatolites. Possible hot spring deposits are nearby.
This 120 mm long piece looks ordinary until you see a few spectacularly preserved 1 mm fibrovascular bundles with cells and vascular structures visible through a microscope.
Photo 1: sharpened photo of 1 mm fibrovascular bundle.
Photo 2: labeled fibrovascular bundle; photo not sharpened. 1: vascular tissue. 2: a bundle cap with sclerenchyma cells. 3: sclerenchyma cells. 4: manmade fiber. 5: fibrous bundle. 6: fibrovascular bundle. 7: space for phloem (not preserved) that transport food. 8: xylem vessels that transport water. 9: parenchyma cells groundmass.
Photo 3: fibrovascular bundle; photo not sharpened.
Photo 4: detail of area 1 in photo 5. Arrow points to best fibrovascular bundle in photos 1-3.
Photo 5: side with best fibrovascular bundles. Area 1 detailed in photo 4. Area 2 is a silicified possible spring deposit or stromatolite.
Photo 6: other side of photo 5. Area 1 is area of dark fibrovascular bundles. Area 2 is the silicified deposits.
Photo 7: 3/4 view showing thickness and white silica coating.
Photo 8: exterior with arrows pointing to elongated fibers typical of Palmoxylon.
Good labeled palm fibrovascular bundles in:
Steur, Hans. FOSSIELE PLANTEN webpage:
Viney, M. (2008). The Virtual Petrified Wood Museum, http://petrifiedwoodmuseum.org
Ture, Joseph A. (Date?). Fossil Palms in Principes, Vol. 11, International Palm Society, p 54.
Good paper on Northern California Pliocene and now Miocene floras. No mention of palmoxylon in the San Francisco Bay/ Northern California area.