Physical Sciences and Mathematics Commons^™

Structural Geology Of The Northern Part Of Oxford Quadrangle, Idaho, Jerrold N. Mayer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The northern part of the Oxford Quadrangle, Idaho, includes parts of the Bannock Range to the west and the Portneuf Range to the east. These ranges are separated by Marsh Valley to the north and Cache Valley to the south. Red Rock Pass, the outlet of glacial Lake Bonneville, divides the two valleys. The mapped area is north of Preston, Idaho, and south of Downey, Idaho. The north-south dimension of the mapped area is 5.2 miles and the east-west dimension is 6.4 miles.

The stratigraphic units, within the mapped area, are Precambrian, Paleozoic, and Cenozic in age. The oldest rock …

Petrology And Mineralogy Of Quaternary Basalts, Gem Valley And Adjacent Bear River Range, Southeastern Idaho, William D. Perkins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Quaternary basalts of Gem Valley, Idaho, are present as valley fill (Group 1) and as well defined flows in the Bear River Range (Group 2) east of Gem Valley. Minerals present in both groups of basalts include olivine (Fo₇₃ -Fo₃₉), augite (Wo₄₁ En₃₉ Fs₂₀), plagioclase (An₇₅ -An₄₀), and Fe-Ti oxides. Coexisting pairs of magnetite and ilmenite, and olivine and clinopyroxene in several samples indicate temperatures of crystallization from 958°c to 1167°c. The Group 2 basalts exhibit a cumulate texture with abundant large (2 cm) phenocrysts of plagioclase.

Chemically, the Gem …

Geology Of North Craters Of The Moon National Monument, Idaho, William C. Sidle

Dissertations and Theses

The purpose of the investigation was to map the geology of the north end of Craters of the Moon National Monument and surrounding area. A stratigraphic sequence of Late Paleozoic sedimentary and Tertiary volcanic rocks was compiles and the structures of these rocks and contact relationships with intrusions were delineated. Grade and facies of contact metamorphism were defined. The Snake River Plain basalts were also mapped. The sources of these flows were determined where possible. Preexisting structures and relationships of vents to earlier faulting were explored in ascertaining extensions of the Great Rift Zone into the Pioneer Mountains. Petrographic descriptions …