Sandstone

Sandstone is just that, stone formed of cemented sand. It is usually too coarse to preserve delicate fossils, but many leaves lurk in the Dakota sandstone of Montana, and hundreds of brachiopods in the Oriskany sandstone of New York. Foraminifera and ostracods, little fossils that are themselves the size of sand grains, are abundant in marine sandstones of the Cenozoic era.

Some marine sandstones include poorly preserved fossil shell molds. Water moved freely through these sands before they became stone, dissolved the shells contained in the sand, and left behind a grainy mold.

Sandstone can also be the hardened relic of a sandy riverbank or lake shore that existed millions of years ago. In Connecticut and Texas, dinosaurs ambled across these ancient shores and left behind their ample footprints. Some even left their mighty bones, too, and shifting river channels covered them with sediment. Such deposits of dinosaur bones are found in many western states. Heedless of such company, worms and bottom dwellers crawled on and in the sandy bottom, leaving behind their own fossil trails.

Shallow ocean bays that existed 275 million years ago collected quanti-

Austin Texas Fossil Clam Photos
Fossils are usually poorly preserved in sandstone, and identification is difficult. These clams are from Kansas.

ties of Coal Age plants, torn loose from swamps near the shore during flood stages and floated out into the bay. There they became buried in sand. This occurred so rapidly in some areas, such as near Ottawa, Kansas, that the plants are found buried upright or at odd angles in the thick sandstone. The plants are preserved as carbon films, detailed enough so

This crab is an example of a well-preserved fossil found in sandstone. Oligocene; Washington.

that the genus of the plant can be identified, but not in as faithful detail as fossils of like plants preserved in the finer-grained shale just a few feet below the sandstone. Large upright logs and stumps were uncovered in Indiana in the last century where sandstone was mined to make millstones.

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  • Ronald
    How to preserve sandstone fossils?
    8 years ago

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