Fig. 4

Diagram illustrating the abrupt continental facies changes that occur at impact-identified KPBs (red line) across the Western Interior (see Fig. 1), with approximate latitude given beneath each area to emphasize the geographic extent of those facies changes (note that these are modern latitudes, and diagrams are illustrative, not to precise stratigraphic scale). Question marks on different facies symbols represent uncertainties or ambiguities about those facies; the question mark on the KPB line in the Denver Basin represents uncertainty about the precise location of the KPB in the mountain-proximal portions of that basin. Note that these are generalized schematics that do not capture all sedimentological or stratigraphic details of a given area—for a more detailed discussion of these different localities, see the Supplementary Discussion. AB Alberta, CAN Canada, CR Castle River area of southern Alberta, CV Coal Valley area of western Alberta, Dist. mountain-distal portions of the Denver Basin, ID’d identified, lat. lateral, MS multistoried, Prox. mountain-proximal portions of Denver Basin, RDV Red Deer Valley Alberta, SS single-storied, UCZ ‘upper coal zone’, USA United States of America.