File:M98Ch2Fig1.JPG

Restored extent of the great American carbonate bank (GACB) during the earliest Ordovician (early Tremadocian) Stonehenge transgression. This transgression occurred during deposition of the Early Ordovician Symphysurina trilobite Zone or during deposition of the Cordylodus angulatus and basal Rossodous manitouensis conodont Zones. This period probably does not represent the maximum transgression during deposition of the Sauk III but is commonly preserved and recognized across Laurentia. The records of younger transgressions, which may have been more extensive, are commonly removed by erosion. Consequently, this map records the maximum documented (at this time) extent of the GACB across Laurentia. Derby, James R., Robert J. Raine, Anthony C. Runkel, and M. Paul Smith, 2012, Paleogeography of the great American carbonate bank of Laurentia in the earliest Ordovician (early Tremadocian): The Stonehenge transgression, in J. R. Derby, R. D. Fritz, S. A. Longacre, W. A. Morgan, and C. A. Sternbach, eds., The great American carbonate bank: The geology and economic resources of the Cambrian–Ordovician Sauk megasequence of Laurentia: AAPG Memoir 98, p. 5–13.