Western Washington University Western CEDAR WWU Graduate School Collection WWU Graduate and Undergraduate Scholarship Spring 1981 Geology and Structure of the Western and Southern Margins of Twin Sisters Mountain, North Cascades, Washington Frederic I. Frasse Western Washington University,
[email protected] Follow this and additional works at: https://cedar.wwu.edu/wwuet Part of the Geology Commons Recommended Citation Frasse, Frederic I., "Geology and Structure of the Western and Southern Margins of Twin Sisters Mountain, North Cascades, Washington" (1981). WWU Graduate School Collection. 639. https://cedar.wwu.edu/wwuet/639 This Masters Thesis is brought to you for free and open access by the WWU Graduate and Undergraduate Scholarship at Western CEDAR. It has been accepted for inclusion in WWU Graduate School Collection by an authorized administrator of Western CEDAR. For more information, please contact
[email protected]. GEOLOGY AND STRUCTURE OF THE WESTERN AND SOUTHERN MARGINS OF TWIN SISTERS MOUNTAIN, NORTH CASCADES, WASHINGTON A Thesis Presented to The Faculty o£ Western Washington University In Partial Fulfillment ^ Of the Requirements for the Degree Master of Science by Frederic I. Frasse June, 1981 GEOLOGY AND STRUCTURE OF THE WESTERN AND SOUTHERN MARGINS OF TWIN SISTERS MOUNTAIN, NORTH CASCADES, WASHINGTON by Frederic I. Frasse Accepted in Partial Completion of the Requirements for the Degree Master of Science June, 1981 Dean of Graduate School Advisory Committee ABSTRACT Detailed mapping of the Goat Mountain dunite and the western and southern margins of the Twin Sisters dunite indicates that the structural setting of these bodies is dominated by high-angle northwest-trending fault zones. The Goat Mountain dunite overlies rocks of the Chilliwack Group and Yellow Aster Complex as a low- angle, west-dipping slab approximately 2500 feet thick.