original |
Late Namurian |
Westphalian A |
Iowa |
Ravn,R.L. et al. A Morrowan, (Upper Carboniferous), miospore flora from eastern Iowa, USA. |
1982 |
original |
Morrowan |
|
Iowa |
Ravn,R.L. Palynostratigraphy of the Lower and Middle Pennsylvanian Coals of Iowa |
1986 |
original |
Morrowan |
|
Iowa |
Ravn,R.L. Palynostratigraphy of the Lower and Middle Pennsylvanian Coals of Iowa |
1986 |
original |
Middle Pennsylvanian |
|
West Virginia |
Kosanke,R.M. Palynological studies of Middle Pennsylvanian Coal Beds of the proposed Pennsylvania system stratotype in West Virginia |
1988 |