Field records from his research trips, 1940-1980

Field records from his research trips, including Glaciated Allegheny Plateau, 1975-80; Sedimentary Appalachian Mts., 1966; Central Rocky Mts., 1966, Red Mtn., Mammoth, Devils River, 1970; Cascade Mts.; Piedmont Plateau: San Bernadino Mts., 1940, 1963, 1968. Additionally, Clausen kept records of his interests in Ithaca and Cornell, such as the Herbarium; Greenhouse in Slaterville Springs; Botany Courses, 1964-5; Taxonomy Courses, 1966; and his personal possesions at Cornell, 1971.