ID: BONNEVILLE CO.
General Description.—Guilday 1969: Also known as Owl Cave. A stratified cave site on the central section of the Eastern Snake River Plain, eastern Idaho. Sedimentation considered by Butler (1968), Dort (1968), and Ore (1968). Over 7,000 individual small mammals recovered by Idaho State Museum during 1966-67. Fill was screened through 3/8" mesh, and isolated teeth were not recovered. Guilday's study based on Block E2B (at least 5,980 individuals), chosen because of central position under a ledge believed to have been an owl roost. Only Thomomys townsendi remains not recovered from the block (those from Block E2C, layer 14 and 16, 180-190 cm). Ca. 4 m of fill.
Age.—Mostly Holocene; some >8,000 BP, based on 14C date (all but Marmota and Spilogale found in latter). Guilday 1969: Estimated dates for layers: Layer 13, 3400 to 2200 BP (est.); Layer 14, 6600 to ca. 3400 BP (14C date); Layer 16 8000 (14C) to 6600 BP (Mt. Mazama ash); Layer 18, 10,500 (est.) to 8000 BP. 12,850 ± 150 (WSU-1281) (Butler 1972); 10,920 ± 150 (WSU-1786) (Miller and Dort 1978); 12,250 ± 200 (WSU-1259) (Sheppard and Chatters 1976). According to Willig and Aikens (1988), the two 12,000+ dates were on bone collagen from mammoth; also the 10,920 date, with the latter believed correct because of Folsom points from site being of about that age.
Paleoenvironment.—Guilday 1969: Apparently semi-desert conditions throughout the period of deposition. Fauna typical of present day fauna, though varying in proportions. Sediments indicate at least three distinct sets of ice-wedges below the 100-cm level, indicating episodes of increased cold separated by periods of lesser cold. Guilday 1969: The rate of sedimentary accumulation decreased on the order of 80% (ave of 7.28 cm per century in layers 16-18; ave of 1.43 cm per century in 13-14). Deposition rate of small mammals in post-Mazama ash period decreased from 136 per century (presumably he means from before this period) to 18.
Guilday 1969: Increasingly evident that an Altithermal cannot be picked up from sites in this region from small mammal successions. "In all probability post Pleistocene conditions have been so harsh in the area that a change from harsh, to harsher, back to harsh, is not reflected in this semi-desert area in relative changes of small mammal species compositions" (p. 50). Guilday 1969: Details changes in percentages of taxa between layers, etc.
Butler 1969: Graphs relative numbers of lagomorphs (primarily Brachylagus) as representative of sagebrush habitat and Thomomys as representative of habitat with more grasses and forbs. He sees a notable shift from pocket gopher to rabbit at around 6600 years ago, presumably recording a climatic shift.
Comments.—Guilday (1969) seems to give good evidence for the presence of both Mustela frenata and M. erminea, but seemingly doesn't trust it and records them tentatively. He also is inconsistent between text and tables in what he "cf."s.
Publications.—Butler 1968, 1969, 1971a, 1971b; (Currey and James 198?); Dort 1968; (*Guilday 1969); Guilday 1972; (Guilday and Parmalee 1972); (Harris 1985); (Kurtén and Anderson 1980); J.N. McDonald 1981; Miller and Dort 1978; Ore 1968. (Agenbroad 1984); Butler 1972, 1978, 1986; Miller and Dort 1978; Sheppard and Chatters 1976;(Willig and Aikens 1988);
Fauna.—
MAMMALIA
Last Update: 18 January 1999.