After Rhodes changed her major to geology, she was taught by other well-known professors such as Edwin B Branson and Maurice G. Mehl.
Through dedicated work and interest, She became a distinguished carbonate stratigrapher and was considered to be an expert on several of the Permian basin rock units.
While she studied at the University of Missouri she also acted as a teaching assistant for geology courses while pursuing her own education.
During this time Rhodes had completed many exploration assignments including in Abilene, San Angelo, Amarillo, Corpus Christi, Texas and Denver.
The experience and knowledge gained first-hand working with Chevron Corporation allowed Rhodes to help educate hundreds in the field.
[11] Examples of the papers she was referenced in is Wellman Field, Terry County, Texas[12] and Exploratory Drilling in 1950.
[13] Rhodes was a noted traveler during her time off, a passion she shared with her two sisters, Ann R. Bradshar of Fort Collins and Doris E. Munroe, who lived with Mary until her death.
She studied and was a Teacher Advisor (TA) at the University of Missouri, where she received her bachelor's and master's degree in Geology.
Her work and her contributions to the geology field were acknowledged and resulted in her being awarded an Honorary Life Membership in the Permian Basin Section of SEPM in 1974.