[2] In 1958, Challis joined the Petrology Section of the New Zealand Geological Survey as a technician.
[3] She undertook a master's degree majoring in geology at Victoria University of Wellington, studying part-time, where in 1959 she won the Sir Robert Stout scholarship for best student.
She later said that one of her supervisors, Harold Wellman, "treated her like an honorary man", such that she was surprised when he brought another lecturer to act as chaperone on a visit to her in the field.
[3] In 1961 Challis won a DSIR scholarship to Cambridge University, where she completed a PhD in geology in 1963, titled The petrology of the New Zealand ultramafic belt.
[3] Also during her PhD, Challis met socially with one of her geology lecturers from Victoria University of Wellington, Ross Lauder.