BUCK'S CANYON ROADCUT FOSSIL HUNT

All photos by CDaniels unless noted otherwise

     On one of Green Mountain's canyon slopes is Buck' Canyon where a road has been cut for a new housing subdivision.  The road cut exposes the strata of Mississippian  limestone, sandstone and shale.   The strata shows evidence of the areas geologic history.  Lots of fossils of crinoids, brachiopods, mollusks, and rugose corals can be found among the rubble of rocks on the base of the road cuts.

• Observation of the rock wall exposing the strata will be documented and discussed.  The historical geology of the area will be reviewed.  Fossils will be identified by general classification if not by species.

1)  Green Mountain and most of Huntsville are underlain by rocks of Paleozoic age (545-245 million years).

 2) The Paleozoic rocks that outcrop on Green Mountain and exposed on Buck's Canyon are limestone, sandstone, and shale of the  Mississippian system (360-320 mil.years old).

    3) The area is generally capped with the Pottsville formation made up of  sandstone, shale and coal.  The Pottsville is of the Pennsylvanian system (320-286 mil. years old).

    4) Shale fragments generally yield fossils since shale splits easily exposing the organisms' form.  But fossiliferous limestone can also get fragmented exposing the organisms that lived over 300 million years ago.

    5)  During the Mississippian and Pennsylvanian periods,  large areas of the Appalachian highland and interior regions were enundated by shallow seas.  Invertebrates were more abundant since only relatively fewer vertebrates have evolved.  The preserved fossils typically had hard shells or exoskeletons that became embedded in and lithified with the sediments.  Also most of the invertebrates then were marine or aquatic.

• The teachers will spend the time looking for fossils.  There are stacks of rock fragments along the new streets of the subdivision.  The area has not been overgrown with vegetation, being so new, and there are a lot of fossiliferous rock fragments scattered along the sides of the streets.  Rocks have been used as riprap to minimize the erosion.

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Crinoid stems.

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 Brachiopods and crinoid stems
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Brachiopod and mollusk.

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Brachiopods, mollusk shells, and crinoid stems
 

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Brachiopod and crinoid stems

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Brachiopods

• Teachers will be able to observe the shale, sandstone, and limestone layers on the rock wall along with a new spring that was formed from the road cut.

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• Once underground, a stream is now exposed as a spring after the rock was cut for the road and subdivision.

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• Shale layers do not allow water to penetrate well and most likely formed a perched aquifer here before being exposed as a spring.

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