Field Trip To Ione Basin--July 27-August 2, 2002

Western Foothills Of The Sierra Nevada

Amador County, California

This is a closeup of the alternating fossiliferous shales and sandstones exposed at the fossil quarry at famous Lygodium Gulch, in the Middle Eocene Ione Formation; the best fossil leaves occur in the thin-bedded, brilliant white, feldspar and biotite-rich shales which are here interbedded with coarser-grained reddish brown sandstones that bear sporadic occurrences of well preserved Eocene leaves. The sedimentary section is clearly of fluvial origin--an accumulation of fine silts and sands derived from repeated overbank runoff due to major episodes of flooding along the interdigitating system of rivers whose runoff eventually emptied into a vast inland sea some 45 million years ago. Image snapped in early afternoon on July 30, 2002.

Please note: All fossil localities in the Ione Formation of Amador County, California, presently occur on private property; explicit permission from the land owners must be secured before collecting fossils there.

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