Previous research on the small mammal population recovered from archeological excavations at the Wasden Site in southeastern Idaho suggests that changing frequency distributions through time represent a shift in climate during the early Holocene from a cooler, wetter regime to a warmer, drier one. This conclusion was re-evaluated using stable carbon and nitrogen isotope analyses of bone collagen from the three species of small mammals examined in the earlier studies: pocket gophers (Thomomys talpoides), pygmy rabbits (Brachylagus idahoensis), and ground squirrels (Spermophilus townsendii). Resulting carbon and nitrogen isotopic values are consistent with known differences in feeding ecology, suggesting high fidelity as proxies for past vegetation (and thus climate) regimes. Patterns of 15N enrichment and increased representation of C4-CAM vegetation observed in the pocket gophers, and to a lesser extent ground squirrels, suggests increasing warmth and/or aridity from the early Holocene until ∼7000 cal yr BP, thus supporting previous hypotheses of climate change on the eastern Snake River Plain. The results highlight the potential contribution of such studies for archeological research by providing additional proxies for environmental conditions that bear on paleoecological adaptations to climatic change, including past human use and occupation of the region.

Trees growing on the Mt. Sedom salt diapir, at the southern Dead Sea shore, were swept by runoff into salt caves and subsequently deposited therein, sheltered from surface weathering. A subfossil Tamarix tree trunk, found in a remote section of Sedom Cave is radiocarbon dated to between ∼ 2265 and 1930 BCE. It was sampled in 109 points across the tree rings for carbon and nitrogen isotopes. The Sedom Tamarix demonstrates a few hundred years of 13C and 15N isotopic enrichment, culminating in extremely high δ13C and δ15N values. Calibration using modern Tamarix stable isotopes in various climatic settings in Israel shows direct relationship between isotopic enrichment and climate deterioration, particularly rainfall decrease. The subfossil Tamarix probably reflects an environmental crisis during the Intermediate Bronze Age, which subsequently killed the tree ∼ 1930 BCE. This period coincides with the largest historic fall of the Dead Sea level, as well as the demise of the large regional urban center of the 3rd millennium BCE. The environmental crisis may thus explain the archaeological evidence of a shift from urban to pastoral culture during the Intermediate Bronze Age. This was apparently the most severe long-term historical drought that affected the region in the mid-late Holocene.