Western Interior Seaway Map List

60 Total time slices

Paleocene60 Ma
Cretaceous-Paleocene65 Ma
Late Maastrichtian 267 Ma
Early Late Maastrichtian 2A 68 Ma
Early Maastrichtian 1B (clinolobatus)69.7 Ma
Campanian-Maastrichtian 3 70.0 Ma
Campanian-Maastrichtian 2 70.4 Ma
Campanian-Maastrichtian 170.8 Ma
Late Campanian 10B (reesidei)72.1 Ma
Late Campanian 9B (compressus)73.5 Ma
Middle Campanian 8B (scotti)77.0 Ma
Middle Campanian 7B (perplexus)78.2 Ma
Middle Campanian 6B (asperiformis)80.0 Ma
Middle Campanian 5B (maclearni)80.4 Ma
Middle Campanian 4B (obtrusus)80.6 Ma
Early Campanian 3 (Baculites sp. weak)80.9 Ma
Early Campanian 2 (Baculites sp. smooth)81.2 Ma
Early Campanian 1 (Scaphites hippocrepis)82.9 Ma
Late Santonian 2 (Desmoscaphites bassleri)84.0 Ma
Middle Santonian 1 (Clioscaphites veriformis)84.9 Ma
Late Coniacian 3 (Scaphites depressus)87.0 Ma
Middle Coniacian 2 (Scaphites ventricosus)87.9 Ma
Early Coniacian 1 (Inoceramus erectus)89.0 Ma
Late Turonian 5 (Scaphites whitfieldi)89.8 Ma
Late Turonian 4 (P. wyomingensis-macombi)90.5 Ma
Middle Turonian 3 (Prionocyclus hyatti)90.9 Ma
Middle Turonian 2 (Colignoniceras woollgari)92.1 Ma
Early Turonian 1 (Watinoceras coloradoense)93.2 Ma
Late Cenomanian 6 (Sciponocerus gracile)94.0 Ma
Late Cenomanian 5 (M. mosbyense)94.3 Ma
Late Cenomanian 4 (P. wyomingense)94.9 Ma
Middle Cenomanian 3 (C. tarrantense)96.0 Ma
Early Cenomanian 2 (N. americanus)98.1 Ma
Early Cenomanian 1 (Neogastroplites haasi)98.3 Ma
Late Albian 6 (Muddy Low stand)100 – 99 Ma
Late Albian 5 (Skull Creek High stand)105 – 102 Ma
Albian 4 (Skull Creek transgression)106 Ma
Albian 3 (Fall River Low stand)107 Ma
Albian 2 (Fall River High stand)110 – 108 Ma
Aptian/Albian (Fall River trans.)113 – 111 Ma
Aptian 2 120 – 115 Ma
Aptian 1 125 – 120 Ma
Barremian 2 128 – 125 Ma
Barremian 1 130 – 128 Ma
Hauterivian 136 – 130 Ma
Valanginian 140 – 136 Ma
Berriasian145 – 140 Ma
Late Jurassic 4 (Kimmeridgian/Tithonian)150 – 148 Ma
Late Jurassic 3 (Kimmeridgian 2)152 – 151 Ma
Late Jurassic 2 (Kimmeridgian 1)155 – 153 Ma
Late Jurassic 1 (Oxfordian)161 – 156 Ma
Middle Jurassic 5 (Callovian)162 – 161 Ma
Middle Jurassic 4 (Callovian)164 – 163 Ma
Middle Jurassic 3 (Bathonian)167 – 164 Ma
Middle Jurassic 2 (Bajocian)170 – 168 Ma
Middle Jurassic 1 (Aalenian/Bajocian)172 – 170 Ma
Early Jurassic 4185 – 175 Ma
Early Jurassic 3190 – 185 Ma
Early Jurassic 2195 – 190 Ma
Early Jurassic 1200 – 195 Ma