Part 1 concerned an occurrence of Miocene spring-deposited tufa in the Barstow Formation, Calico Mountains, southern California. Part 2 is about another Miocene occurrence of spring-deposited tufa, 118 miles to the southeast of the Barstow locality, in the Diligencia Formation in the Orocopia Mountains, northeast of Salton Sea, Riverside County, California.
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| Google Earth (2018) image, |
The Diligencia Formation spring-tufa deposits resemble fossil "logs," as shown above. These "logs" occur mainly as branching-horizontal tubes, in contrast to the mostly vertical buildups of the Barstow Formation spring-tufa deposits. The Diligencia tufa deposits are confined to a single thin bed that crops out for a least 6 km. This bed represents a lake-shoreline environment, which interfingers with basalt flows and river-delta deposits. The hammer, which is the same one shown in all the subsequent images, is 27 cm in length.
The Diligencia tufa tubes, are commonly parallel to bedding, can be up to 65 cm in length and 25 cm in diameter. Hammer is 27 cm length.
This is a horizontal tube, which has been extensively weathered.
In some places, the Diligencia tufa deposits are transported accumulations of closely packed tubules concentrated into a thin bed of limestone.
In other places, the Diligencia tufa deposits occur as scattered, weathered remains.
All the Diligencia tufa deposits consist predominantly of wavy microcrystalline calcite laminations surrounding by small core that is filled with darker sediment and/or partly with coarser grained calcite. The "dime" coin is 18 mm in diameter.
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