Quaternary geology and structural history of the Snake River Plain, Idaho and Oregon

Molecular systematics and radiation of western North American nymphophiline gastropods

“…1, Table 1) was similarly mapped onto the tree to evaluate geographical diversification of Pyrgulopsis. Geographical regions, whose characteristic physiography and structure generally date to the late Tertiary (Stewart, 1998), were chosen as the unit of analysis rather than major western drainage basins, which have been shown to be complex composites (e.g.. Belcher, 1975;Malde, 1991;Young, 2004).…”

Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho

“…Malad Gorge is a tributary to the Snake River Canyon, Idaho, within the Snake River Plain, a broad depression filled by volcanic flows that erupted between ∼15 Ma and ∼2 ka (22,23). The gorge sits at the northern extent of Hagerman Valley, a particularly wide (∼7 km) part of the Snake River Canyon (Fig.…”

A molecular phylogeny of aquatic gastropods provides a new perspective on biogeographic history of the Snake River Region

“…Biotic distributions instead have been used to infer that the ancestral Snake River flowed through southeast Oregon to the California Pacific coast, via either the Klamath (Taylor, 1960(Taylor, , 1985 or Sacramento (Miller, 1965) Rivers (also see Wheeler and Cook, 1954). Although this hypothesis is well entrenched in the literature (Christiansen and Yeats, 1992;Malde, 1965Malde, , 1991Smith et al, 2000), its supporting biogeographic evidence has never been rigorously evaluated.…”

“…The only reasonably well established geological benchmark that can be associated with this postulated paleodrainage is the capture of the Snake River by the Columbia River, which is generally thought to have occurred about 2.0 Ma (Malde, 1991;Othberg, 1998; Sadler and Link, 1996) in conjunction with the draining of Lake Idaho and incision of Hells Canyon. [Note that some workers have suggested that this shift in drainage occurred earlier in the Pliocene (e.g., Link and Fanning, 1999;Smith, 1999;Wood, 2000) and thus we consider 2.0 Ma to be a minimal date for this event.]…”