Hellam Township
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A scenic waterfall in "Accomac Gorge."  The bedrock is the Catoctin Formation metabasalt.  Combined with the exposures in the stream and the roadcut just to the south, make this one of the largest exposures of the oldest formation within the Hellam Hills.  Metarhyolite is also found in the area.  The presence of these rocks prove that volcanoes did occur in York County approximately 700-800 million years ago.  Other areas where these volcanic rocks can be found include near the Hellam interchange of U. S. Route 30 in the Hellam Hills and in the Pigeon Hills near Hanover. dcp00043.jpg (44208 bytes)
Hellam Township - In "Accomac Gorge",  the stream shows an evolutionary history of potholes.  Here, these potholes are formed within the Catoctin Formation metabasalts.

Hellam Township - The most widespread formation within the Hellam Hills is the Chickies formation.  One member, the Hellam Conglomerate occupies some of the higher elevations.  A conglomerate is a sedimentary rock that contains rounded pebbles.  In this case, the pebbles are composed of quartz.  The rock is one of the oldest sedimentary rocks in Pennsylvania dating back 570 million years ago.  Geologists think that this rock was formed in a delta environment.

Hellam Township - Codorus Furnace is one of five iron furnaces that once existed in York County.  This furnace located on the east side of the Codorus Creek near the junction with the Susquehanna River has been rebuilt and is currently owned by the Conservation Society of York County.  The furnace operated in the late 1700's into the mid 1800's processing iron ore mostly  removed from the Earth in the Hellam Hills of York and Chestnut Ridge in Lancaster County.  codorus.jpg (108008 bytes)
Hellam Township -  Shull's Rock provides one of the most scenic pictures of the Susquehanna River in York County.  The rock is composed of the Chickies Formation quartzite.  Here looking north, notice the railroad bridge in the foreground.  In the distance is Brunner's Island, a coal-generation electric plant.  To the right is the Lancaster County Solid Waste facility near Bainbridge.  Notice above the railroad bridge a line crossing the river.  This is a "riffle" in the water where the Stoneybrook diabase dike crosses into Lancaster County.  The diabase is more resistant to weathering and erosion compared to the surrounding rock.    Please note, Shull's Rock is on private property and trespassing will not be tolerlated.

 

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Hellam Township - At Shull's Rock, excellent examples of Scolithus tubes are visible.  In this example, these are at the top of the bed (looking down on the tubes).  Each circle represents a tube.  These tubes are believed to have been formed by a worm boring its way through the sand some 600 million years ago.  When a geologist finds these worm tubes like in this case, it helps the scientist to determine which way the beds are oriented.  Photo by Mary Ann Schlegel

 

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Hellam Township - Chimney Rock is a classic site of the Hellam Conglomerate, the lowest member of the Chickies formation. The rock is over 600 million years old and contains mostly rounded quartz pebbles. Weathering and erosion has formed these two pinnacles over time. This rock is a great teaching tool for structural geology classes. Stretched pebbles and lineations help to interpret the structural geology of the Hellam Hills. On private property, permission has to be obtained from the owners. Check out www.seechimneyrock.com.
   

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