Sunday, September 7, 2014

fossil pine cones

a fossil pine cone, height 10.5 cm

I have always been intrigued by fossil pine cones, especially the ones that were transported by river currents to a ocean shoreline and ended up being deposited in the shallow-marine environment alongside Turritella shells (see some of my earlier posts) and shark teeth. 

The rare specimen shown above is from float material (weathered out and laying loose on the surface) from the Pico Formation near Newhall, southern California. The formation in this area was deposited in a marine-delta environment. There had to have been pine trees growing in the adjacent, ancient San Gabriel Mountains east of the delta. This pine cone floated down a braided river (full of coarse debris consisting of pebbles and cobbles) and was deposited in fine-grained sandstone near the ancient shoreline. 
another fossil pine cone, height 8.5 cm

The rare specimen shown above is from float material found near Topanga State Beach, southern California. Much less is known about its provenance (origin) than the Pico Formation specimen.

Identification as to the family or genus of pine tree for both of the illustrated specimens is needed. The identification process is not an easy task. Just the presence of pine cones in a sedimentary rock deposit is most helpful, nevertheless, because they indicate that a mountainous area was adjacent to the burial site.

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