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![]() PETRIFIED WOOD Gymnosperms or conifers, and angiosperms, the flowering plants, are the two main types of seed plants which generate woody material. These woody plants are capable of adding yearly growth layers of cells onto previous growth. These "growth rings" reflect the different rate of growth between the growing season and the dormant season. Generally, a dark ring signifies the dormant season, and a light band signifies the growth season. Wood is a collection of various kinds of cells whose shape, size and relationship assist in its identification. Pores, resin cells, resin canals, rays and other parts of cell structure are examined during identification and play a large part in the wood's beauty. Petrified wood forms when the cell structure of the wood is preserved by the deposition of mineral material such as silica, pyrite, or calcium carbonate along the cell walls. The material either replaces or encloses the organic remains and, as a result, often retains the structural detail of the original wood. Petrified wood is very important botanically, because it is generally from petrified materials that the internal structure of the plant can be studied. The colors which make petrified wood so spectacular are caused by iron, manganese or the organic matter, itself. As an example, the red coloration in a piece of petrified wood may be due to small amounts of the iron oxide mineral called hematite. Petrified woods are studied by cutting and grinding portions of them into thin sections. The cell structures of these translucent sections can then be studied under the microscope. Kern County is famous for its petrified wood, and the Isch's exhibits at our museum are fine local examples. Most local petrified wood comes from Miocene or Pliocene sediments on the eastern San Joaquin Valley or volcanic ash-rich sediments of the same age in the Mojave Desert. Petrification occurs where organic matter is lying a poorly oxygenated environment. Back then, the local climate was much like the Central Coast today, and bodies of water were rich with minerals from volcanic glass and silica materials which dissolved in lakes and ponds. Volcanic mud flows uprooted plant matter burying logs, stems and roots so the petrification process could begin. In general, petrified woods which show the best cell structure don't have much color. Kern County's petrified wood is generally brown, tan, black or a combination of these colors. However, these colors still seem to add to the real beauty of our petrified wood, which comes from their magnificent detail in cellular structure. Stop by the museum and admire our collection. Donations are tax deductible Click on the Cymbospondylus for more information Web Master: Sherry Pauley Internet service connection courtesy of: |
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