The Lebanon Valley, along with regions to the east and west, is covered with a broad swatch of pink – the color indicative of sedimentary rocks dating to the Ordovician period.

Specifically, the region boasts “carbonate and clastic sedimentary rocks,” according to the legend accompanying a new online map from the U.S. Geological Survey, and “includes some metasedimentary rocks primarily in the Appalachian orogen.”

In layman’s terms, as explained by the National Park Service , the Ordovician period lasted for 41.6 million years, ranging from 485.4 million years ago to 443.8 million years ago. During that period, the park service explains, “marine fauna increased fourfold,” with the seas teeming with bivalves, gastropods (snails), bryozoans (moss animals), and crinoids (sea lilies). The

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