Assertion: cave's history | /r/HasProperty | limited to early ordovician periods
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Source sentences:
text: Geologic history recorded in the sedimentary rocks and surficial deposits of Pictured Rocks National Lakeshore is limited to two widely separated intervals of geologic time, the Late Precambrian, Cambrian, and Early Ordovician Periods (500-800 million years before present), and the Late Quaternary Period (two million years before present to the present).