The Physiographic History of Western Montana and Northwestern Idaho

Millions of years of physiographic changes have conditioned us to the fact that our present drainage is a temporary feature. Rivers once flowing opposite to their present direction is not an unusual condition for physiographers to suggest.

Geochronology and isotope geochemistry of Eocene dykes intruding the Ladakh Batholith

In order to determine the extent and timing of dyke formation in the Ladakh Batholith we examined about 30 mostly andesitic dykes intruding the Ladakh batholith in a ca. 50 km wide area to the west of Leh (NW India). The dykes in the east of the area trend E-NE and those in the west trend N-NW. The difference in orientation is also evident in the petrography and isotopic signatures. The eastern dykes contain corroded quartz xenocrysts and show negative ε0(Nd) and positive ε0(Sr) values, where as the western dykes do not contain quartz xenocrysts and exhibit positive ε0(Nd) and near-zero ε0(Sr) values. The variability in Sr-Nd isotopes (ε0(Nd) = 3.6 to −9.6, ε0(Sr) = 0.4 to 143) and the quartz xenocrysts can best be explained by (differing degrees of) crustal assimilation of the parent magma of the dykes. Separated minerals from five dykes were dated by 40Ar-39Ar incremental heating: amphibole ages range between 50 and 54 Ma, and one biotite dated both by Rb-Sr and by 40Ar-39Ar gave an age of 45 Ma. One dated pseudotachylyte sample attests to brittle faulting at ca. 54 Ma. The combination of structural field evidence with petrographic, isotopic and geochronological analyses demonstrates that the dykes did not form from a single, progressively differentiating magma chamber, despite having formed in the same tectonic setting around the same time, and that processes such as crustal assimilation and magma mixing/mingling also played a significant role in magma petrogenesis.

Middle Devonian fishes from the Lemhi Range of Idaho / [by] Robert H. Denison --

v.16:no.10(1968)

Early Devonian lungfishes from Wyoming, Utah, and Idaho / [by] Robert H. Denison --

v.17:no.4(1968)

Water levels in selected wells and directions of ground-water movement near Fort Hall, Fort Hall Indian Reservation, Southeastern Idaho /

Mode of access: Internet.

Stratigraphy of the unsaturated zone and uppermost part of the Snake River Plain aquifer at Test Area North, Idaho National Engineering Laboratory, Idaho /

Mode of access: Internet.

Bankruptcy rules of the United States District court for the district of Idaho.

Mode of access: Internet.

Radioactive waste management : a bibliography of publicly available literature pretaining to the USAEC's National Reactor Testing Station, Idaho /

"August 1973."

Evaluation and system description of ASAP judicial systems. Volume III: Idaho case study. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Idaho city : queen of the gold camps /

Mode of access: Internet.

Impact of discontinuing Idaho's periodic motor vehicle inspection program (a before and after outage rate study).

Mode of access: Internet.

Impact of discontinuing Idaho's vehicle inspection program - before study. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Enforcement and public information strategies for DWI general deterrence: the Boise City, Idaho experience. Final report.

National Highway Traffic Safety Administration, Office of Driver and Pedestrian Research, Washington, D.C.