As Sanderson and her two sisters grew old enough for school, the farm was sold, and the MacDonalds moved to their paternal great-grandfather's original homestead in Howick.
She graduated with a BSc in 1949, and followed it with an MSc on the petrography of Jurassic conglomerates at Kawhia, encouraged by Professor John Arthur Bartrum.
Sanderson did much of her fieldwork for her thesis on horseback, with the help of field assistants Charles Laws, Alan Mason, and Helen Pirie.
[1] Sanderson's work involved identifying geological samples brought in by the general public, and preparing and examining thin-sections for research.
[2] Robin Sanderson had been working at the British Geological Survey but shortly after their marriage he took a curatorial position at the Natural History Museum.
[1] Sanderson's example inspired geologist Heather Nicholson to undertake a field-based MSc, mapping Waiheke island, completed in 1954.