AN INTERPRETATION OF THE STRATIGRAPHIC POLLEN RECORD AT THE MILL IRON SITE, SOUTHEASTERN MONTANA

Previous pollen analysis at the Mill Iron site has yielded evidence of
local vegetation at the time of the Goshen occupation, as well as throughout
portions of the stratigraphic record between that time and the present (Scott
1985; Cummings 1987). The first study (Scott 1985) examined sediments that
yielded radiocarbon ages between 1270 and 4570 BP and indicated that pollen
preservation was sufficient to undertake a more thorough stratigraphic study of
the pollen record. Consistency between this record and others from the Little
Missouri Badlands was noted. A stratigraphic pollen column was collected from
the excavation block during the 1986 field season. Radiocarbon ages from the
bone bed in this area varied from 10760 to 11360 BP. The pollen record
encompassed samples immediately below the bone bed, from the bone bed, and
between the bone bed and the present surface. In addition, samples were
collected from the present surface to provide information on modem pollen rain.
The summer of 1986 was relatively wet and vegetation was relatively lush. This
pollen record indicated local vegetation dominated by Artemisia below the bone
bed, throughout the occupation, and for a considerable part of the pollen record.
A dramatic change was noted approximately half way up the column when Cheno-ams
increased briefly, then Cyperaceae increased dramatically, replacing both Cheno-ams
and Artemisia in the record. This record indicates that at 11,000 BP there
was no spruce forest in the vicinity of the Mill Iron site. The vegetation was
typical of a mixed sagebrush/grass prairie. There is an indication in the
record, however, that pines were more numerous near the base of the record,
declining shortly after the Goshen occupation.