This is a really cool lady! In 1929, she organised a dig at Great Zimbabwe, with an all woman team, and declared that the site was built by an African civilisation. Which did not go down at all well in South Africa! Her views on the matter are now generally accepted, however. Zimbabwe is thought to mean "great houses of stone" in the Shona language, and the name has been attached to all ruins of this type across the region. There are around 200 of them, though Great Zimbabwe is the biggest and most impressive.
Here's a picture of some of the ruins, which gives an idea of the scale of the place, from the blog Zimtree:
Her work also helped to confirm the medieval dating of the site, which later excavation has shown to have been continuously inhabited from the twelfth to the fifteenth century, with the bulk of the finds coming from the fifteenth century.
Gertrude Caton Thompson got her experience as an archaeologist in Egypt, where she worked with Margaret Murray, Flinders Petrie and Dorothea Bate, and later with the British School of Archaeology, where her digs were characterised by her precision - it's routine now to plot the precise position and depth of artefacts, but it was a new idea in the 1920s.
She was a research fellow at Newnham College Cambridge, and the first female president of the Prehistoric Society as well as a founding member of the British School of History and Archaeology in East Africa.