The plant megafossil collections from the Tolstoi Formation contain three distinctive assemblages. The oldest assemblage can be recognized in the collections from the lower part of the sections on Ivanof Bay, Windy Bay, and the sections on Kiukta Bay, Chignik River, and the old collections on Anchorage Bay. This assemblage is characterized by species such as Cocculus flabella, Chaetoptelea microphylla, Fagopsis sp., Carya antiquora, and Dicotylophyllum richardsonii. In Alaska, the correlative of this part of the Tolstoi is in the upper (but not uppermost) part of the Chickaloon Formation and the lower part of the West Foreland Formation. This assemblage is of early late Paleocene age.

The second assemblage is characterized by the highest occurrence of typical Paleocene species such as Thuites interrruptus and Protophyllum semotum. Also included, however, are the lowest occurrences of certain extant genera, for example, Liquidambar, Eucommia, Platycarya, and Lamanonia. This assemblage probably occurs in the uppermost part of the Chickaloon Formation, which has been radiometrically dated at 55 Ma. In conterminous United States, this assemblage occurs in the Golden Valley Formation of the Dakotas, associated with mammals of early Wasatchian age. Although the Wasatchian has been traditionally correlated with the early Eocene, recent analyses indicate that, in the widely accepted planktic chronology, the earliest Wasatchian is of latest Paleocene age; this interpretation is adhered to here and the middle Tolstoi assemblage is considered to be of latest Paleocene age.

The youngest Tolstoi assemblage is that collected from the Painter Creek section. This assemblage lacks any typical Paleocene species but contains Platycarya pseudobraunii, Pterocarya nigelloides, and ”Viburnum” variabilis, all of which are typical Eocene species. At least the upper part of the Painter Creek section is thus of early Eocene age.

Most of the collections submitted contain some determinable leaf impressions; a majority of these collections, however, contain species that have not been recognized elsewhere and are thus at the present time of no biostratigraphic value. I suspect that the basic problem is that most of these collections represent the youngest Tolstoi assemblage, which is much more diverse than the lower assemblages. Thus, in the instances of small collections such as those submitted, the probability of collecting representatives of species that occur in other collections is low until such time as the upper Tolstoi assemblage in the Painter Creek section is thoroughly collected.

The following localities have the oldest assemblage: 11411-11413, 11597, 11435-11438, 11603, 11602, 11405, 11406, 11409, 11410, 11626, 11627, 11632. The following localities have the middle (latest Paleocene) assemblage: 11415-11417, 11604, 11628, 11635. The youngest (early Eocene) assemblage is found at localities 11577-11580.

Locality 11632 (your 78 Arh 62) was placed in the Chignik Formation, but the flora is indicative of early Tolstoi age. Conversely, your 78 Adt 8, assigned to the Tolstoi, is certainly in the Chignik.

The collections from the lower part of the Stepovak on Ivanof Bay are of late Eocene age. Although not as diverse, the lower Stepovak assemblage contains several species that also occur in the Meshik collection. The lower part of the Stepovak is thus correlated with the Meshik at locality 11605. The list of fossils from particularly locality 11605 is deceptively small; the flora from this locality is, in fact, diverse (at least 30 species are represented). Almost all the species, however, are new to science and have not yet been found at other localities in the Alaskan Eocene.

Most of the species listed from the lower Stepovak and Meshik are broadleaved deciduous. The material from locality 11605, however, includes many broadleaved evergreen species, including members of Lauraceae and Theaceae. From this I infer that mean annual temperature was certainly in excess of 13 deg., C. Also supporting an interpretation of a warm, mild climate are the woods from field locality 7720 in the lower Stepovak. A cursory and preliminary examination of these woods by R. A. Scott indicated the presence of a diverse hardwood element that included several diffuse porous wood; such woods are typically (although not entirely) found today in warm to hot climates that have abundant precipitation.

Your suggestion that locality 11629 (your 77 ADt 94) might be in Meshik rather than Tolstoi rocks is substantiated by the plant megafossils.

The small collection from the Bear Lake Formation (locality 11631) contains indeterminable species of Alnus and Salix. These genera are common in Alaskan Oligocene and Neogene floras and thus are allowable evidence for your stratigraphic assignment of the locality to the Bear Lake.